EXCEA 


LIBRARY 

OF-THE 

UNIVERSITY  OF  CALIFORNIA, 

RECEIVED    BY   EXCHANGE 

Class 


O&ile  Press,  Inc. 
New   V'ork  City 


TYPICAL    METHODS    OF    THINKING 

IN 

SCIENCE    AND    PHILOSOPHY 
BY 


LUCAS    CARLISLE    KELLS 

I 


A    DISSERTATION 

SUBMITTED    IN    PARTIAL    FULFILMENT    OF    THE 

REQUIREMENTS    FOR    THE    DEGREE    OF    DOCTOR 

OF     PHILOSOPHY     IN     THE 

FACULTY    OF    PHILOSOPHY 
COLUMBIA     UNIVERSITY 

NEW    YORK 
1910 


K4 


CONTENTS 


CHAPTER  I. 

PAGE 

1 .  Darwin's  Theory  of  the  Origin  of  Species 1 

2.  Hyslop's  Theory  of  a  Life  After  Death 3 

3.  Locke's  Theory  of  Human  Understanding 6 

4.  The  Theory  of  Ions 8 

5.  The   Theory   of   Inorganic   Evolution 10 

6.  The  Theory  that  Matter  is  Electrical 11 


CHAPTER  II. 


PAGE 
Classification   and   Comparison   of  Theories 13 


CHAPTER  III. 
QUALITIES  OF  THEORIES 

PAGE 

1 .  Believability    of    Theories 19 

2.  Simplicity  of  Theories 21 

3.  Verifiability    of   Theories 30 

4.  Meaning  of  Truth  of  a  Theory 35 

5.  In  what  Sense  do  Theories  Explain 36 

6.  Usefulness   of   Theories 36 

227361 


CHAPTER    I. 


A  study  of  modern  theories  in  science  and  philosophy  reveals 
very  contrasted  methods  of  thinking.  By  some  of  these  methods 
conclusions  have  been  reacted  which  are  recognized  as  valuable 
acquisitions  to  the  store  of  useful  knowledge,  while  by  other  methods, 
conclusions  have  been  reached  which  have  never  gained  wide 
recognition  and  which  have  remained  independent  of  the  general 
evolution  of  thought. 

We  may  hope  to  benefit  by  our  experience  with  thinking  and 
by  a  comparative  study  of  past  efforts,  may  discover  principles 
which  will  guide  us  to  fruitful  results  in  the  future.  The  purpose 
of  this  thesis  is  to  study  a  number  of  typical  theories  in  science 
and  philosophy,  to  compare  and  classify  them,  to  analyze  the  method 
of  procedure  in  each,  to  consider  the  simplicity,  believability  and 
usefulness  of  each;  and  thus  to  draw  conclusions  as  to  the  com- 
parative value  of  the  different  methods  used  in  deriving  the  theories. 

The  theories  considered  will  be:  Darwin's — "Origin  of  Spe- 
cies," Hyslop's — "Science  and  a  Future  Life,"  Locke's, — 
"Essay  Concerning  Human  Understanding,"  "The  Theory  of  Ions," 
"The  Theory  of  Inorganic  Evolution,"  and  ''The  Theory  of  Matter 
as  Electrical.*' 

STATEMENT  AND  ANALYSIS  OF  DARWIN'S  THEORY  OF  THE 
ORIGIN  OF  SPECIES. 

Darwin  in  his  theory  of  "The  Origin  of  Species"  reasons  as  fol- 
lows:— Under  domestication,  we  find  much  individual  variation  in 
both  animals  and  plants.  The  causes  of  the  variations  are  many, 
complex,  and  little  understood;  but  for  the  purposes  of  the  theory 
the  variations  may  be  taken  to  be  perfectly  indefinite  or  of  chance 
occurrence.  Some  are  variations  of  structure  and  some  of  function. 


Some  make  the  creature  more  desirable  for  human  purposes  and 
some  less  desirable.  Man,  by  selecting  and  breeding  from  individ- 
uals having  favorable  variations,  has  produced  widely  diverse  breeds, 
adapted  to  his  various  purposes.  In  nature,  we  find  individual 
variations  of  the  same  kind  that  we  find  under  domestication  indefi- 
nite or  approximately  chance  variations.  We  also  find  in  nature 
a  selecting  agency;  the  struggle  for  existence.  Of  the  vast  num- 
ber of  offspring  born  each  year  of  animals  and  plants,  a  greal 
percentage  perish  because  not  well  enough  adapted  to  the  surround- 
ings in  which  they  are  born.  Those  individuals  having  variations 
favorably  adapting  them  to  the  conditions  of  life  will  more  often 
survive  than  those  not  having  such  variations.  The  surviving  individ- 
uals will,  individual  variations  being  hereditary,  breed  their  kind; 
from  their  offspring,  selection  will  again  be  made;  and  this  process 
continuing  from  generation  to  generation,  through  long  periods  of 
time,  will  give  rise  to  breeds,  often  quite  diverse  and  each  well 
adapted  to  live  under  the  conditions  of  life  in  which  it  has  been  pro- 
duced. It  is  admitted  that  varieties  have  been  thus  produced  and 
Darwin  concludes  from  his  argument  that  this  also  was  the  manner 
of  the  origin  of  species. 

Similarities  in  organic  structure  and  vital  functions,  in  animals  of 
distinct  species,  suggested  to  Darwin  the  possibility  of  a  common 
origin.  This  was  a  natural  hypothesis.  It  perhaps  would  be  among 
the  first  theories  that  would  occur  to  a  thinker,  seeking  an  explana- 
tion of  such  similarities.  From  experience  with  phenomena,  it  has 
become  natural  to  expect  relationship  where  we  find  similarity.  The 
theory  then  which  occurred  to  Darwin  was  one  which,  if  suggested 
to  any  other  thinker  having  knowledge  of  the  facts  with  which  Darwin 
was  acquainted,  would  have  seemed  quite  possible  to  him. 

A  common  origin  was  the  natural  inference  from  the  phenomena 
of  marked  similarities,  similarity  being  so  often  to  our  knowledge  the 
result  of  relationship;  but  this  inference  raised  the  question,  by  what 
means  came  the  diversity  to  be.  For,  until  it  was  shown  how  the 
diversity  came  from  the  common  origin,  the  theory  of  a  common 
origin  would  not  possess  great  certainty ;  but  if  it  could  be  shown  that 
there  were  forces  operating  which  would  produce  the  diversity,  then 
the  theory  would  gain  greatly  in  strength. 

Darwin  turned  to  nature  in  quest  of  the  forces  which  he  believed 
must  have  worked  and  still  were  working  to  produce  species.  When 
he  consulted  his  experience  he  found  under  human  control  a  process 
by  which  diverse  breeds  were  produced  from  a  common  stock  of 
animals.  To  understand  fully  this  process  and  its  possibilities, 
Darwin  experimented  for  many  years.  He  then  turned  to  nature 

[2] 


and  found  there  analogous  variations  from  which  selection  might 
take  place  and  a  selecting  agency,  the  operations  of  which  he  care- 
fully studied.  The  analogy  was  complete,  man  selecting  from  the 
offspring  of  a  common  stock,  produces  diverse  breeds  suited  to  his 
purposes;  nature  by  the  struggle  for  existence,  selects  from  varying 
offspring  and  produces  diverse  species  suited  to  live  under  diverse 
conditions. 

Thus  Darwin  answered  the  main  question  raised  in  his  thinking 
by  performing  an  experiment.  When  the  question  arose:  how  were 
species  derived  from  a  common  origin?  Darwin  answered  it  by 
producing  species  from  a  common  stock.  He  then  investigated  nature 
and  found  that  it  imitated  the  processes  which  he  had  performed  in 
his  experiment. 

Darwin  in  his  thinking  and  in  his  experiment  conceives  the 
things  about  which  he  thinks  and  with  which  he  deals,  just  as  the 
ordinary  man  conceives  them.  Similarities  in  structure  and  function, 
individual  variations,  the  struggle  for  existence,  heredity,  and  all  the 
other  things  and  functions  involved  in  the  theory  are  such  as  could 
be  explained  to  the  ordinary  man  without  his  changing  the  character 
of  his  conceptions  of  the  things  about  which  he  was  told.  In  all 
cases  the  things  considered  are  such  as  are  presentable  in  experience. 
Pigeons,  species,  variations,  the  struggle  for  existence,  all  are  such 
things  as  Darwin  could  identify  in  the  world  about  which  he  was 
thinking.  And  when  he  identified  these  things,  he  took  them  to  be 
just  what  he  found  them  to  be.  He  took  pigeons  to  be  what  any  man 
would  find  them  to  be  who  examined  them.  In  no  case  would  his 
conceptions  be  disputed,  and,  if  they  were,  the  dispute  could  be 
settled  by  reference  to  the  thing  conceived,  for  it  was  from  this 
alone  that  Darwin  pretended  to  draw  his  iaformation. 

Darwin  went  to  nature  as  one  believing  that  it  would  upon  investi- 
gation reveal  its  own  reality.  When  he  made  an  inference,  he  made 
that  one  which  experience  had  taught  him  was  the  most  probable 
implication  of  the  facts  from  which  the  inference  was  made.  When 
a  question  arose  as  to  what  processes  existed  in  nature  and  what  was 
the  consequence  of  their  operation,  he  went  to  nature  and  experiment 
to  determine.  And  in  all  his  thought  and  experiment  he  conceived 
things  to  be  what  they  discovered  themselves  to  be  in  his  experience. 

STATEMENT  AND  ANALYSIS  OF  HYSLOP'S  THEORY  OF  LIFE 
AFTER  DEATH. 

Belief  in  a  future  life  implies  a  belief  in  supersensible  reality  and 
a  belief  in  survival  of  personal  consciousness. 

[3] 


Scientific  thought  is  continually  dealing  with  supersensible  reali- 
ties, so  the  existence  of  the  supersensible  will  not  be  doubted.  If 
then  there  are  occurrences  which  no  other  known  theory  will  explain, 
we  must  for  the  present  accept  the  theory  of  the  existence  of  discarnate 
spirits. 

Super-normal  knowledge  and  personal  identity  exhibited  by  com- 
munications through  Mrs.  Piper  as  medium  are  occurrences  explain- 
able by  no  other  known  hypothesis.  Therefore  we  must,  until  some 
better  hypothesis  is  found,  accept  the  theory  of  spirits. 

Prof.  Hyslop  like  Darwin  experimented.  But  Darwin  by  his 
experiment  was  showing  that  his  explanation  was  a  true  one,  while 
Hyslop  by  his  experiments  is  gathering  facts  to  be  explained.  Prof. 
Hyslop  performed  no  experiment  to  show  that  his  explanation  was  a 
possible  one. 

The  following  facts  with  other  similar  facts  furnish  the  founda- 
tion for  Prof.  Hyslop's  theory.  Mrs.  Piper,  a  medium,  goes  into  a 
trance  state.  While  in  this  state,  questions  are  asked  of  her,  to 
which  neither  she  in  her  normal  state  nor  the  questioner  knows  the 
answer.  These  questions  are  answered  correctly,  questions  are  asked, 
and  other  communications  are  given  by  or  through  the  medium. 
These  communications  are  so  given  as  to  appear  to  be  given  by 
some  person  known  to  be  dead.  And  sometimes  the  communications 
are  such  as  to  make  it  appear  that  one  person  is  conversing  with 
another,  all  of  whom  are  known  to  be  dead.  Mistakes  and  con- 
fusions occur  as  if  memories  had  failed  or  as  if  those  appearing  to 
communicate  had  not  adequate  means  of  communication.  These 
are  the  facts  of  evidence  for  the  theory  and  also  the  facts  to  be 
explained  by  the  theory.  Everything  that  is  said,  is  spoken  by  the 
mouth  of  Mrs.  Piper;  but  what  she  says  purports  to  be  the  com- 
munications of  others. 

No  other  theory  adequately  explains  these  facts;  all  other  known 
theories  are  therefore  excluded  from  belief.  Prof.  Hyslop  thus 
advocates  belief  in  the  theory  of  survival  after  death. 

Prof.  Hyslop's  theory  implies  the  existence  of  a  number  of 
facts.  These  facts  implied  are :  that  in  the  human  make-up,  there  is  a 
part  never  yet  discovered  to  science;  that  upon  death  this  part  does 
not  die  but  becomes  separated  from  the  body  and  leads  an  indepen- 
dent existence;  that,  though  in  life  there  seems  to  be  closest  depen- 
dence between  physical  and  mental  functions,  yet  that  this  spirit  dis- 
engaged, carries  on  the  mental  functions,  little  impaired,  after  the 
decay  of  the  physical  being;  that  these  spirits,  possessed  neither  of 
eyes,  ears,  vocal  organs,  nor  any  of  the  known  organs  of  perception 
and  communication,  nevertheless  do  perceive  things  of  the  world  and 

[4] 


of  each  other,  and  do  communicate  with  each  other  and  with  living 
men;  that  either,  they  in  communicating  to  us,  move  the  entranced 
subject  to  speak  what  they  would  have  her  speak,  or  her  volition  being 
dormant,  a  spirit  takes  possession  of  her  organs  and  operates  them 
as  a  man  would  a  typewriter,  making  her  speak  mechanically  the 
thoughts  of  the  communicating  spirit. 

These  are  the  facts  implied  by  the  theory  and  I  shall  here  briefly 
repeat  the  facts  of  evidence  for  them.  An  entranced  subject  speaks 
in  answer  to  questions  and  imparts  supernormal  pieces  of  knowledge; 
the  things  which  she  speaks  purport  to  be  communications  from  per- 
sons no  longer  living;  what  she  says  sometimes  purports  to  be  con- 
versation between  dead  persons ;  and  there  are  mistakes  and  confusions 
such  as  we  should  expect  from  persons  with  failing  memories  or  with 
deficient  means  of  communication. 

We  note  that  here  there  is  no  direct  evidence  of  the  existence  of 
such  a  part  as  the  spirit  in  the  human  make-up.  And  all  experiments 
relative  to  that  question  tend  to  indicate  that  if  there  were  such  a 
part  and  if  it  were  essential  to  mental  functioning,  that  it  ceases 
to  function  when  the  physical  organs  are  injured  or  destroyed 
Neither  does  Prof.  Hyslop  perform  any  experiments  nor  offer  any 
evidence  to  show  that  spirits  can  perceive  and  communicate.  Nor  is 
any  explanation  given  of  how  they  can  communicate  without  organs 
of  perception  and  communication  known  to  us.  There  is  then  no 
experimental  evidence  in  the  theory  leading  to  an  inference  of  the 
existence  of  spirits;  and  no  experiments  are  performed  to  show  how 
spirits  can  perceive  and  communicate  or  to  lead  to  an  inference  that 
they  can. 

We  have  thus  far  exhibited  the  evidence  offered  for  the  theory 
and  the  conclusions  and  implications  of  the  theory.  We  now  call 
attention  to  the  fact  that  the  conclusions  and  implications  concern 
things  of  whose  nature  and  abilities  we  have  no  experimental  evidence 
and  no  experience.  And  we  also  note  that  these  things  about  which 
the  theory  is  concerned  are  like  nothing  in  experience.  Prof.  Hyslop's 
thinking  then,  reveals  this  peculiarity:  that  whereas  evidence  usually 
leads  us  to  infer  that  something  out  of  experience  is  like  something  in 
experience;  in  Hyslop's  thinking  we  find  an  inference  from  evidence 
in  experience  of  what  things  out  of  experience  exist  and  of  what  they 
are  like,  when  they  are  like  nothing  in  experience.  From  certain 
manifestations  in  experience  the  existence  of  spirits  and  their  powers 
are  inferred.  As  spirits  are  like  nothing  in  our  experience,  we  can- 
not infer  that  they  produced  the  manifestations  because  of  their 
likeness  to  something  in  experience  producing  such  manifestations; 
and  the  theory  as  we  have  found  it,  offers  no  experiments  to  show  that 

[5] 


spirits  can  produce  such  manifestations  or  how  it  is  possible  for  them 
to  do  so. 


LOCKE'S  THEORY  OF  HUMAN  UNDERSTANDING. 

The  reasoning  of  Locke's  theory  is  as  follows:  Reality  is  con- 
stituted of  three  different  kinds  of  things  with  their  relationships.  The 
three  kinds  of  things  are  minds,  ideas,  and  bodies.  The  mind  is  a 
receptive  medium  in  which  ideas  arise  by  virtue  of  the  operations  of 
matter  or  body.  Anything  which  is  present  to  the  mind  is  an  idea. 

Ideas  are  impressions  made  upon  the  mind  and  are  of  two  kinds: 
those  caused  by  the  primary  qualities  of  objects  and  those  caused  by 
the  secondary  qualities  of  objects.  A  quality  of  an  object  is  the 
power  in  it  to  produce  ideas.  The  primary  qualities  produce  ideas 
which  copy  them  or  resemble  them;  the  secondary  qualities  do  not 
produce  resembling  or  copying  ideas  in  the  mind.  The  secondary 
ideas  are  mere  perceptions  in  the  mind;  the  primary  are  modifications 
or  matter  which  cause  ideas  in  us  resembling  them.  It  results  from 
the  nature  o-f  these  two  kinds  of  ideas  that  secondary  qualities  reveal 
to  us  nothing  of  the  real  object,  while  knowledge  of  primary  qualities 
is  "real  knowledge,"  knowledge  of  "real  existence." 

Knowledge  is  the  perception  of  the  connection  of,  and  agreement 
or  disagreement  of,  ideas.  Thus  the  originals  of  knowledge  are 
ideas  of  sensation  impressed  upon  the  mind  by  matter  and  knowl- 
edge is  limited  by  the  existence  and  nature  of  ideas. 

Thus  Locke  concludes  his  task.  He  sought  the  originals,  cer- 
tainty, and  extent  of  human  knowledge:  he  found  its  originals  in  the 
ideas;  its  extent  in  the  limits  of  their  relationships;  and  its  certainty 
dependent  upon  the  directness  with  which  the  mind  perceives  those 
relationships. 

The  problem  which  Locke  sought  to  solve  was  one  of  definition 
and  origin.  He  asked:  what  is  knowledge  and  in  what  manner  does 
it  come  to  be.  As  we  have  seen,  Locke  succeeds  in  answering  both 
questions.  We  are  here  interested  in  determining  by  what  method  he 
reaches  his  conclusions. 

Locke  entered  upon  his  thinking  with  a  certain  conception  of 
mind.  He  conceives  the  mind  to  be  an  empty  cabinet  into  which 
ideas  get;  or  a  plastic  medium  upon  which  they  are  impressed.  This 
conception,  he  takes  for  valid  without  question.  Such  a  mind  is  not 
directly  revealed  in  experience  and  Locke  performed  no  experiments  in 
search  of  evidence  for  its  existence  or  for  its  nature.  He  assumed  both 
to  be  as  he  conceived  them. 

This  conception  of  mind  which  Locke  assumed,  involved  in  it 

[6] 


necessarily  his  conception  of  an  idea.  If  the  mind  is  an  empty  cabinet, 
ideas  must  be  .of  a  nature  to  be  contained  in  it  in  some  way :  or  if  the 
mind  is  a  plastic  medium,  the  idea  must  be  a  modification  of  it  or  an 
imprint  upon  it.  Thus  by  assuming  the  nature  of  mind  Locke  has  by 
implication  also  assumed  the  nature  of  ideas. 

Also  in  Locke's  conception  of  mind  is  bound  up  his  conception  of 
the  real  outer  world.  For  Locke  conceives  the  mind  to  be  a  passive 
medium,  and  ideas  to  be^jere  modifications  or  imprints.  The  modifi- 
cations can  then  only  arise,  if  some  active  principle  operates  upon  the 
mind  to  modify  it.  This  active  principle  is  matter  or  body.  Thus  it 
appears  that  when  Locke  made  his  original  assumption  of  the  nature 
of  the  mind,  he  likewise  assumed  the  nature  of  the  idea  and  of  body. 
These  three  constitute  the  whole  of  Locke's  reality. 

The  solution  of  Locke's  problem,  the  statement  of  the  nature, 
certainty  and  extent  of  human  knowledge  is  a  direct  logical  deduction 
from  his  conceptions  of  mind,  matter  and  idea.  And  these  we  have 
found  to  be  bound  up  together  in  his  conception  of  mind.  The  mind 
can,  by  assumption,  concern  itself  only  with  ideas;  knowledge  is  a 
mental  function ;  knowledge  must  concern  itself  only  with  ideas.  Thus, 
the  extent  of  knowledge.  As  knowledge  is  not  an  idea  nor  a  group  of 
ideas,  it  must  be  of  the  relationship  of  ideas.  Thus  the  nature  of 
knowledge.  As  the  mind  perceives  the  relationships  of  ideas  with 
different  degrees  of  directness,  different  degrees  of  clearness  or  cer- 
tainty result.  Thus  the  explanation  of  the  degrees  of  certainty  of 
human  knowledge. 

The  same  method  of  assumption  and  deduction  is  revealed  in 
Locke's  theory  of  "real  knowledge."  He  assumes  that  some  ideas 
copy  or  resemble  reality  and  some  do  not;  and  that  we  can  know 
which  do  copy  and  which  do  not.  This  assumption  is  not  grounded 
on  experience  and  Locke  did  not  investigate  to  determine  its  validity. 
From  this  assumption  it  follows  in  Locke's  reasoning,  that  some  knowl- 
edge is  real  or  reveals  to  us  the  nature  of  real  existence. 

We  conclude  from  this  examination  that  Locke's  method  of  think- 
ing consists  in  making  an  assumption  and  drawing  out  the 
natural  implications  of  that  assumption.  Locke  assumes  the  mind  to 
be  a  plastic  medium;  it  follows  that  ideas  are  modifications  or  imprints 
and  that  some  active  principle  operates  to  produce  them.  Knowledge 
being  a  mental  function,  must  concern  itself  with  ideas  and  be  limited 
by  the  number  of  ideas  and  their  relationships. 

The  theory  thus  derived,  has  some  peculiarities  to  be  noted.  The 
mind  which  is  assumed  to  exist  is  like  no  thing  in  experience  which 
we  can  examine  and  determine  the  qualities  of.  Therefore  we  can 
infer  nothing  as  to  its  nature.  Neither  was  such  a  mind  discovered 

[7] 


by  Locke  and  investigated  so  as  to  reveal  its  properties.  Being  like 
nothing  in  experience,  a  modification  of  the  mind  or  an  impression 
upon  it,  is  like  no  modification  or  impression  of  which  we  know. 
Therefore  the  nature  of  the  idea  and  the  manner  of  its  origin  are 
unintelligible  to  us.  Neither  is  the  manner  in  which  the  ideas  re- 
semble or  copy  objects  like  any  resembling  or  copying  of  which  we 
know.  Therefore  th»  manner  in  which  ideas  copy  or  resemble 
things,  we  cannot  comprehend. 

This  statement  of  the  theory,  its  method  of  procedure,  and 
characteristics  will  serve  as  a  basis  for  study  and  comparison  in 
connection  with  the  other  theories  here  dealt  with. 

THE  THEORY  OF  IONS. 

Another  type  of  thinking  is  represented  by  the  theories  presented 
in  Duncan's  "The  New  Knowledge."  The  theories  are  as  follows. 
Upon  examination,  the  atomic  weights  of  many  of  the  elements  are 
found  to  be  approximately  whole  numbers.  The  elements  can  be  ar- 
ranged in  groups  having  closely  resembling  qualities  and  having  con- 
stant relations  between  their  atomic  weights.  In  short,  it  is  found 
that,  "the  properties  of  an  element  are  a  periodic  function  of  its 
atomic  weight."  This  law  has  been  many  times  confirmed  in  differ- 
ent ways. 

Now  the  scientist  reasons  thus:  either  the  elements  were  created 
(or  are)  each  unique  in  substance  and  structure  and  the  relations  be- 
tween them,  expressed  by  the  periodic  law,  are  chance  relations;  or 
the  atoms  of  elements  are  complex,  and  uniformities  in  their  struc- 
tures will  explain  uniformities  in  their  properties.  Only  if  this  latter 
hypothesis  is  true,  can  we  explain  the  periodic  law. 

But,  because  the  assumption  that  the  atom  is  complex  in  struc- 
ture is  the  only  one  upon  which  the  periodic  law  can  be  explained, 
the  scientist  does  not  take  this  assumption  to  be  established  theory,  but 
begins  to  investigate  to  determine  the  validity  of  the  assumption. 

He  finds  that  groups  of  atoms  unite  together  to  form  bodies  with 
related  properties  and  group  relationships,  and  he  finds  that  groups  of 
atoms  unite  and  act  like  elements.  Thus  the  scientist  reasons,  that 
if  combinations  of  atoms  may  act  like  elements  and  may  form,  by 
variation  in  number  and  arrangement,  compounds  related  as  the  ele- 
ments are  related,  is  it  not  probable  that  sub-atoms  form  elements  and 
by  their  number  and  arrangements  furnish  an  explanation  of  the 
periodic  law? 

But  more  direct  evidence  of  the  complexity  of  the  atom  is  de- 
manded and  obtained  by  the  scientist.  He  finds  that  gases  under 
certain  conditions  have  an  increased  conductivity.  When  the  gas  is 

[8] 


filtered,  it  loses  this  increased  conductivity.  Thus  something  is 
filtered  from  the  gas,  which  gave  it  conductivity.  This  something  can 
also  be  taken  from  the  gas  by  passing  it  through  a  space  in  which 
there  is  a  current  of  electricity.  Only  particles  could  be  caught  in  a 
filter  and  only  electrified  particles  would  be  drawn  from  the  gas  by 
a  current  of  electricity.  As  the  gas,  as  a  whole,  does  not  change,  the 
particles  must  be  both  positive  and  negative.  Once  having  discovered 
these  particles,  the  scientist  experiments  with  them.  He  subjects  them 
to  electrical  forces  and  by  their  motions  determines  their  charge, 
velocity  and  weight  by  the  familiar  formulae  of  Physics.  He  finds 
them  one-thousand  times  smaller  than  the  smallest  atom;  alike  in 
nature  and  size  and  that  they  constitute  an  actual  part  of  the  matter 
from  which  they  fly.  He  controls  them  so  as  to  produce  chemical, 
heating  and  mechanical  effects  and  thus  arrives  at  a  more  intimate 
knowledge  of  them.  He  finds  that  they  give  rise  to  x-rays  in  bodies 
which  they  strike;  that  they  are  absorbed  by  all  bodies  in  direct 
proportion  to  the  density  of  those  bodies;  and  that  they  act  as  nuclei 
about  which  atoms  and  molecules  collect.  These  corpuscles  are  given 
off  by  elements  in  their  natural  state,  by  radium,  uranium,  polonium, 
actinium,  air,  etc.  As  these  different  substances  continually  emit  these 
particles,  one-thousand  times  smaller  than  atoms,  it  is  reasonable  to 
believe  the  atoms  constituted  of  them.  This  belief  is  strengthened 
when  we  find  that,  as  the  corpuscles  are  emitted  by  some  substance 
as  radium  or  thorium,  their  atoms  continually  change,  forming  en- 
tirely new  elements.  As  the  same  atom  in  some  cases  breaks  down 
into  many  different  atoms,  the  original  must  have  been  complex. 

Before  proceeding  with  the  next  step  in  the  establishment  of  the 
theory,  a  brief  summary  will  be  of  value.  The  scientist  on  investiga- 
tion finds  the  elements  definitely  related.  The  relations  are  too 
numerous  and  too  extended  to  be  explained  by  chance.  The  scientist 
can  only  hope  to  explain  them,  if  the  atom  is  complex.  He  finds  par- 
ticles existing  much  smaller  than  atoms.  From  the  fact  that  atoms 
continually  emit  them  and  in  emitting  them  continually  change  into 
atoms  of  different  kinds,  the  scientist  believes  the  atom  complex  and 
constituted  of  these  smaller  particles  called  ions  or  corpuscles.  In 
his  procedure  thus  far,  the  scientist  has  assumed  nothing.  He  has  in- 
vestigated the  things  about  which  he  wished  information ;  he  has  foand 
the  atom  to  be  complex  and  of  what  it  is  constituted  by  examining  it 
by  every  possible  means  known  to  him.  Although  these  atoms  and 
corpuscles  manifest  themselves  to  none  of  his  senses;  yet  he  controls 
them  by  forces  familiar  to  him  and  leads  them  to  produce  familiar 
effects,  from  which  he  can  infer  their  nature  with  a  certainty  which 
no  one  understanding  his  procedure  will  question. 

[9] 


But  how  does  the  scientist  proceed  from  the  knowledge  he  has 
thus  gained,  to  an  explanation  of  the  periodic  law?  He  has  found 
the  atom  complex;  he  has  found  it  constituted  of  ions  some  positively 
and  some  negatively  charged.  He  now  makes  an  assumption.  He 
assumes  the  positive  charge  to  be  a  spherical  shell  surrounding  the 
negatively  charged  particles.  Granting  this  assumption,  the  structure 
of  atoms  containing  various  numbers  of  corpuscles  can  be  mathe- 
matically calculated;  and  the  variations  of  structure  with  different 
numbers  of  corpuscles  in  the  atom  are  such  as  to  explain  in  detail, 
the  Periodic  Law,  Group  relations  of  elements.  Series  Relations, 
Prout's  Hypothesis,  the  Triads  of  Dobereiner,  valency,  chemical 
action,  the  zero  group,  Radio  activity,  and  unstable  atoms.  When  it 
is  said  that  the  variations  of  structure  explain  the  variations  of  prop- 
erties, it  is  meant  that  there  are  periodic  recurrences  of  the  same 
structure  where  there  are  periodic  recurrences  of  the  same  quality. 
There  are  uniformities  in  structure  corresponding  to  the  uniformities 
in  property. 

It  is  evident  that  in  this  step  in  the  theory,  the  scientist  has  changed 
his  method  of  procedure.  Up  to  this  step,  he  had  established  all  upon 
an  experimental  basis.  Here  he  attempts  to  establish  a  step  in  his 
theory  upon  other  grounds.  That  the  atom  is  a  spherical  shell  of 
positive  electrification  surrounding  negative  charges,  he  does  not  verify 
experimentally.  He  assumes  that  it  is  true  and  according  to  the 
established  laws  of  physics,  finds  that  the  structural  relations  will  be 
such  as  to  explain  the  chemical  to  a  remarkable  degree.  The  validity 
of  the  assumption  rests  alone  on  its  explaining  power.  The  Atom  may 
not  be  formed  as  assumed;  it  may  be  but  accidental  that  if  it  were, 
all  that  correspondence  between  physical  and  chemical  relations  would 
result,  yet  such  chance  occurrences  are  so  anomalous  in  our  experience, 
that  where  we  find  such  perfect  correspondence  we  faithfully  seek  for 
dependency.  And  when  in  an  experimental  chain,  we  are  at  a  loss 
for  a  link  and  we  find  one  fitting  perfectly,  our  experience  has  been 
such  that  we  take  it  as  very  probable  that  such  a  perfect  fitting  is  not 
accident,  but  that  our  assumed  link  is  really  existent  and  perhaps  some 
day  to  be  experimentally  revealed. 


THE  THEORY  OF  INORGANIC  EVOLUTION. 

The  scientist's  method  of  procedure  is  also  well  illustrated  by  the 
theory  of  inorganic  evolution  presented  in  Duncan's  "New 
Knowledge."  Some  elements  such  as  radium  and  uranium  are  found 
to  be  actually  evolving  into  other  elements.  Elements  at  different 

[10] 


temperatures  give  different  spectra,  which  means  that  they  decompose 
into  other  elements.  The  temperature  of  different  parts  of  the  sun 
and  of  the  same  parts  at  different  times,  and  of  the  stars,  can  be  ob- 
served. With  small  changes  of  temperature  in  the  sun,  different 
forms  of  the  same  elements  appear;  with  great  changes  of  temperature 
some  elements  disappear  and  new  elements  appear.  In  the  stars  there 
is  a  great  range  of  temperature.  In  stars,  differing  little  in  temperature, 
we  find  different  forms  of  the  same  element.  But  in  stars  differing 
greatly  in  temperature,  entirely  different  elements  exist.  Beginning 
with  the  hottest  stars,  we  have  elements  of  the  smallest  atomic  weight 
and  as  we  pass  from  cooler  to  cooler  stars,  the  elements  of  heavier 
and  heavier  atomic  weight  appear.  As  the  heavier  atomic  weight  in- 
variably appear  in  the  cooler  stars,  we  believe  that  the  heavy  atoms 
have  evolved  from  the  light  atoms,  which  alone  are  found  in  the 
hottest  stars. 

We  note  that  the  evidence  is  of  observed  relations  between  the 
elements  under  different  conditions.  The  scientist  observes  directly 
the  gradual  dissolution  of  radium  and  uranium  into  other  elements. 
He  can  with  the  small  range  of  temperature  under  his  control,  ma- 
terially change  many  elements.  He  observes  the  sun  and  sees  the 
heavier  atoms  appear  as  the  sun  spots  dwindle  and  disappear  as  the 
sun  spots  approach  the  maximum.  And  in  the  stars,  which  give  him 
the  greatest  range  of  temperature,  he  observes  the  relation  between 
temperature  and  the  existence  of  atoms  of  different  weights.  As 
certainly  and  as  directly  as  we  see  a  seed  germinate  and  grow  into 
a  tree,  does  the  scientist  see  the  lighter  atoms,  as  the  temperature 
falls,  change  into  atoms  of  heavier  weight.  To  be  sure,  he  does  not 
view  the  atom  change  directly,  but  he  views  the  lines  in  his  spectro- 
scope, which  he  has  learned  by  experience,  faithfully  represent  the 
atoms;  and  they  tell  with  equal  certainty  the  history  of  the  evolving 
atom.  In  acquiring  this  knowledge,  the  scientist  has  made  neither 
assumption  nor  inference.  He  has  simply  read  the  report  of  the 
spectroscope,  the  trustworthiness  of  which  long  experience  has  taught 
him. 

THE  THEORY  THAT  MATTER  Is  ELECTRICAL. 

By  experiment  it  was  found  that  atoms  were  composed  partly 
of  corpuscles,  and  that  corpuscles  were  small,  negatively  charged 
bodies  moving  with  great  velocity.  The  mass  of  these  corpuscles, 
when  at  rest,  was  experimentally  compared  with  their  mass  when  in 
motion.  The  supposition  was  then  made  that  the  corpuscles  were 
merely  electrical  charges;  and  the  mass  when  at  rest  and  in  motion, 


was  computed  on  this  supposition.  The  results  agreed  with  the  actual 
masses  as  experimentally  determined.  That  the  mass  of  a  small  body 
electrically  charged  greatly  increases  as  its  velocity  approaches  that 
of  light  is  an  experimental  fact.  As  matter  is  made  up  of  such  small, 
rapidly  moving,  charged,  corpuscles,  part  at  least  of  its  mass  must 
be  electrical  in  origin.  But  the  scientist  infers  that  its  mass  is  entirely 
electrical  in  origin;  for  if  it  were  entirely  electrical  in  nature,  its  mass 
would  be  just  what  its  mass  in  fact  is.  In  other  words,  the  scientist 
takes  mass  to  be  the  distinguishing  characteristic  of  matter;  he  then 
finds  that  an  electrical  charge  has  exactly  this  same  characteristic.  It 
may  be  that  matter  is  not  electrical  in  nature  and  that  this  correspon- 
dence is  accidental.  Yet  the  theory  that  matter  is  electrical  has 
strength;  for  in  our  experience  such  an  accidental  correspondence 
would  be  an  anomaly.  Here  again  the  scientist  has  made  an  as- 
sumption which  so  strikingly  fits  a  place  in  an  evidential  chain,  that 
its  validity  seems  a  credible  inference. 

Thus  far,  we  have  attempted  to  state  the  theories  which  we  wish 
to  study ;  to  reveal  the  important  steps  in  the  procedure  by  which  each 
was  derived ;  and  to  note  the  dominant  characteristics  of  the  resulting 
theories.  In  the  succeeding  chapter  we  shall  compare  and  classify  the 
theories  in  question. 


[12] 


CHAPTER  II. 
CLASSIFICATION  AND  COMPARISON  OF  THEORIES. 

I  have  found  in  considering  the  theories  stated  that  they  may  be 
conveniently  classified  from  two  points  of  view.  When  viewed  from 
the  point  of  view  of  method  of  procedure  in  deriving  the  theory,  there 
are  two  distinct  classes;  and  when  viewed  with  respect  to  the  nature 
of  the  problem  solved  as  a  basis,  there  are  two  well  defined  classes. 

We  shall  first  consider  the  classes  of  theories  from  the  view-point 
of  problem  solved.  The  first  class  of  theories  under  this  head  con- 
sists of  those  which  have  for  their  object  to  explain  the  origin  or 
existence  of  things  or  relations  between  things  by  showing  the  manner 
in  which  these  things  or  relations  were  produced.  Darwin's  theory  of 
"The  Origin  of  Species"  falls  under  this  class.  His  problem  was  to 
explain  how  well  defined  species  of  animals  and  plants  came  to  be 
formed;  and  his  solution  consisted  in  showing  that  individual  varia- 
tions with  natural  selection  would  give  rise  to  species  in  nature  as 
similar  processes  do  in  case  of  domesticated  animals.  Hyslop's  prob- 
lem and  solution  were  of  the  same  nature.  He  sought  to  explain  the 
origin  of  supernormal  knowledge,  and  did  so  by  inferring  that  spirits 
of  departed  persons,  who  were  possessed  of  the  knowledge  in  question, 
still  existed  and  imparted  the  information  through  the  living  medium. 
So  also  the  theory  of  ions  belongs  to  this  class.  The  problem  there 
was  to  explain  the  origin  or  existence  of  the  well  defined  relation- 
ships existing  between  the  chemical  elements,  and  expressed  by  the 
Periodic  Law.  The  relationships  were  explained  by  showing  the 
complexity  of  the  atom  and  the  periodic  variation  in  the  number  and 
arrangement  of  the  ions  in  the  atom.  And  lastly,  the  theory  of 
Inorganic  Evolution  has  the  same  kind  of  problem  and  solution. 
The  problem  was  to  explain  the  existence  of  the  many  elements  in 
nature  and  their  origin.  The  solution  consisted  in  showing  the  trans- 
formation from  one  element  into  another  with  varying  degrees  of 
temperature.  Thus  these  theories  illustrate  a  class  in  which  the 
question  is  asked:  how  came  certain  things  or  relations  to  be?  and  is 
answered  by  revealing  the  process  of  origin. 

Now  there  is  from  the  point  of  view  of  problem  and  method  of 
solution,  a  second  class  of  theories.  Those  theories  which  seek  to 
determine  the  essential  qualities  of  things  or  relations  by  defining 
them.  John  Locke  in  his  Theory  of  Human  Knowledge,  seeks  to 

[13] 


determine  the  nature  of  knowledge,  and  solves  the  problem  by  defining 
knowledge  to  be  the  perception  of  the  connection  of^and  agreement 
or  disagreement  of  ideas.  However,  Locke  also  sought  into  the 
origin  of  knowledge,  and  set  forth  the  process  by  which  it  was 
produced.  This  part  of  his  theory  falls  under  the  first  class  of 
theories  in  which  the  problem  was  that  of  origin;  and  solution  that 
of  revealing  process.  We  find,  that  the  theory  that  matter  is  electrical 
is  also  a  theory  of  definition.  The  problem  was  to  determine  what 
matter  essentially  is;  and  the  solution  consisted  in  showing  that  matter 
is  electrical  in  nature.  Thus  the  theories  examined  reveal  two  dis- 
tinct classes  of  theories  from  the  point  of  view  of  problem  and 
method  of  solution. 

They  also  exhibit  two  well  defined  classes  from  the  point  of  view 
of  the  method  of  procedure  by  which  the  theories  were  derived.  The 
method  of  procedure  in  one  class  consists  of  observation  and  experi- 
ment, and  inference  from  facts  thus  revealed.  Some  of  the  theories 
in  this  class  make  use  of  an  occasional  assumption. 

I  shall  first  treat  of  those  theories  which  proceed  by  observation 
and  experiment  and  do  not  make  use  of  assumptions.  Darwin's 
theory  is  such.  He  observed  the  individual  variations  of  plants  and 
animals  in  nature  and  under  domestication.  He  also  observed  how 
man  selects  the  variations  which  suit  plants  and  animals  to  his  pur- 
poses, and  how  nature  selects  those  variations  which  fit  the  organism 
to  live.  He  experimented  to  determine  more  fully  how  great  indi- 
vidual variations  were  and  how  much  change  could  be  produced  by 
accumulating  them  in  the  off-springs.  Thus  Darwin  determined  the 
existence,  nature,  and  extent  of  individual  variation  and  natural  se- 
lection, by  observation  and  experiment.  Observation  also  revealed 
the  nature  of  past  organic  life,  the  remains  of  which  had  been  de- 
posited in  the  Earth's  crust.  The  inference  of  which  this  theory 
consists  followed  directly  from  these  observed  and  experimental  facts, 
without  the  assumption  of  the  existence  of  any  others  or  of  their 
nature. 

The  theory  of  inorganic  evolution  was  derived  by  the  same  method 
of  procedure.  The  transformations  of  elements  under  different  de- 
grees of  temperature  producible  by  artificial  means,  and  exhibited 
by  solar  conditions  and  in  the  stars,  were  observed  and  carefully 
investigated.  The  inference,  that  diversity  of  elements  had  originated 
by  virtue  of  changes  in  temperature,  was  based  directly  upon  these 
observed  and  experimental  facts. 

There  are  some  theories  which  make  use  of  the  same  method  of 
procedure  but  also  contain  occasional  assumptions.  The  theory  that 
matter  is  electrical  is  such.  It  is  not  shown  by  a  direct  investiga- 

[14] 


tion  of  matter  that  it  is  electrical  in  nature.  But  by  experiment,  the 
essential  characteristics  of  electricity  are  determined.  By  the  same 
method  the  qualities  of  matter  are  revealed.  The  reasoning  then  pro- 
ceeds in  this  manner:  Assume  matter  to  be  purely  electrical,  and  its 
essential  qualities  can  be  explained;  therefore  we  infer  matter  to  be 
electrical.  Thus  the  assumption  because  of  its  explaining  power  be- 
comes an  inference  and  is  no  longer  purely  hypothetical. 

So  also  the  theory  of  ions  though  based  fundamentally  upon  the 
experimental  method,  makes  use  of  a  similar  assumption.  The 
existence  of  the  ion,  its  size,  weight  and  properties  are  experimentally 
revealed.  The  theory  then  proceeds  by  assuming  that  the  ions  are 
arranged  with  a  spherical  positive  electrical  charge  surrounding  the 
negatively  charged  ions.  There  is  no  direct  experimental  evidence 
supporting  this  assumption;  but  grant  it  to  be  true,  and  from  the 
known  properties  of  ions,  their  numbers  and  arrangements  in  the 
atom  will  be  such  as  to  explain  to  a  remarkable  degree  the  Periodic 
Law.  Thus  this  assumption  because  of  its  explaining  power  be- 
comes one  of  the  inferences  constituting  the  theory. 

Thus  the  examination  of  the  theories  considered  in  this  paper 
reveals  a  class  derived  by  the  method  of  observation  and  experi- 
ment, some  of  the  theories  making  no  use  of  assumptions  and  others 
using  assumptions  which  from  their  explaining  power  become  in- 
ferences. 

The  theories  in  question  exhibit  a  second  distinct  class  from  the 
point  of  view  of  method  of  procedure.  A  class  from  which  the 
thinker  proceeds  by  assuming  the  existence  and  nature  of  things  which 
have  not  been  experimentally  investigated  and  which  are  like  no 
things  in  experience.  His  further  procedure  consists  in  developing 
the  logical  implications  of  the  assumptions  made.  Such  a  method 
of  thinking  is  John  Locke's  in  his  theory  concerning  human  under- 
standing. Locke  assumes  a  mind  to  exist  and  that  it  has  a  certain 
receptive  or  plastic  nature.  This  assumption  is  in  no  way  founded 
upon  observation  or  experiment.  And  as  the  mind  is  like  nothing  in 
experience,  Locke  did  not  infer  its  existence  by  analogy.  The  mind 
and  its  qualities  are  purely  hypothetical.  In  setting  forth  Locke's 
theory,  we  have  already  shown  that  the  nature  of  the  idea,  the 
nature  of  matter  and  the  nature  of  knowledge  were  all  implied  in  the 
assumed  nature  of  mind;  and  that  Locke's  further  procedure  con- 
sisted in  developing  these  implications. 

Hyslop's  thinking  shows  the  use  of  the  same  method.  Locke 
had  the  fact  of  knowledge  given  and  sought  to  explain  its  origin 
and  nature.  He  did  so  by  assuming  a  mind  of  a  certain  nature  to 
exist.  Similarly,  Hyslop  has  the  fact  of  supernormal  knowledge 


given  and  seeks  to  explain  its  origin.  He  does  so  by  assuming  the 
existence  of  spirits  with  certain  powers.  Like  the  mind  of  Locke's 
theory,  these  spirits  are  not  things  directly  manifest  in  experience; 
and  no  experiments  were  performed  yielding  evidence  of  their  existence 
or  of  their  powers.  The  fact  of  the  existence  of  spirits  and  of  their 
powers  is  purely  hypothetical,  and  by  these  hypotheses  supernormal 
knowledge  is  explained. 

The  difference  between  the  use  of  assumption  in  Locke's  and 
Hyslop's  theories  and  its  use  in  the  theory  of  ions  and  of  the  electrical 
nature  of  matter,  a  difference  which  will  be  fully  considered  later, 
should  here  be  noted.  In  the  theory  that  matter  is  electrical  and  in 
the  theory  of  ions,  the  assumption  is  only  of  the  existence  of  things 
like  things  in  experience.  Concretely  in  the  theory  that  matter  is  elec- 
trical, it  is  assumed  that  electricity  exists  in  the  form  of  matter; 
and  in  the  theory  of  ions,  it  is  assumed  that  the  atom  consists  of  a 
certain  arrangement  of  ions.  It  was  not  necessary  to  assume  what  the 
qualities  of  electricity  are  and  it  was  not  necessary  to  assume  what 
would  result  from  the  certain  arrangement  of  ions;  these  both  were 
experimental  facts.  For  this  reason  we  found  that  assumptions  in 
these  theories  had  great  explaining  power  and  that  the  explaining 
power  was  evidence  of  the  validity  of  the  assumptions.  Contrast 
the  situation  in  the  theories  of  Locke  and  Hyslop.  Here  the  assump- 
tion is  of  the  existence  of  things  out  of  experience  like  no  things  in 
experience.  Concretely,  in  Locke's  theory  minds  were  assumed  to 
exist,  and  in  Hyslop's  spirits.  From  the  fact  that  the  assumed  things 
were  like  nothing  in  experience,  the  powers  of  these  things  were  not 
known,  as  they  were  in  the  case  of  the  theory  of  ions,  and  of  elec- 
trical matter.  Hence  it  was  necessary  for  Locke  to  assume  that  the 
mind  had  certain  powers  and  qualities,  and  for  Hyslop  to  assume  that 
spirits  had  certain  powers  and  qualities.  Then,  when  these  powers 
or  qualities  were  manifested  in  experience,  it  could  not  be  inferred 
that  the  assumed  mind  or  spirits  existed;  for  it  was  not  known,  but 
only  assumed,  that  minds  or  spirits,  as  the  case  may  be,  could  pro- 
duce such  manifestations.  Thus  the  explaining  power  of  the  as- 
sumptions made  in  Locke's  and  Hyslop's  theories  did  not  lead  to  an 
inference  of  the  validity  of  those  assumptions;  while  as  we  have 
seen,  in  the  theory  of  ions  and  the  theory  of  matters  electrical  nature, 
it  did  so  lead. 

From  the  fact  that  the  qualities  and  powers  of  minds  and  spirits 
are  assumed  in  the  theories  of  Locke  and  Hyslop,  and  from  the  fact 
that  minds  and  spirits  are  assumed  to  be  things  unlike  anything  in 
experience,  there  is  no  limit  to  the  powers  or  qualities  that  may  be 
ascribed  to  minds  or  spirits,  as  the  case  may  be.  If  by  ascribing  a 

[16] 


certain  nature  to  mind  Locke  could  not  have  given  an  account  of 
the  origin  of  human  knowledge,  he  could  have  ascribed  any  other 
desired  qualities  to  the  mind  necessary  in  order  to  obtain  an  ex- 
planation ;  and,  if  by  ascribing  certain  powers  to  spirits  Hyslop  could 
not  have  accounted  for  the  phenomena  to  be  explained,  he  could,  at 
will,  have  assumed  the  spirits  to  have  other  powers,  and  have  adapted 
the  assumed  nature  of  spirits  to  the  requirements  of  the  case. 

When,  however,  the  assumption  is  that  a  thing  out  of  experience 
is  like  something  in  experience,  the  nature  of  the  thing  in  experience 
whose  qualities  we  know,  limits  and  controls  our  assumption.  When 
it  is  assumed  in  the  theory  of  ions  that  an  atom  consists  of  a  spherical 
shell  of  electrification,  surrounding  a  number  of  negatively  charged 
particles,  it  cannot  be  or  it  is  not  assumed  that  an  atom  has  any 
different  or  other  qualities  than  such  a  spherical  shell  of  electrification 
containing  charged  particles  would  have.  Our  assumption  is  limited 
and  controlled  by  our  experience  with  such  electrically  charged 
bodies;  and  if  the  qualities  which  we,  by  experiment,  find  such  bodies 
to  have,  will  not,  when  ascribed  to  the  atom,  explain  the  phenomena 
in  question,  the  theory  will  be  abandoned  or  modified  by  assuming 
the  atom  to  £>e  like  some  other  thing  in  experience  whose  qualities 
we  know.  From  the  nature  of  the  assumption  that  matter  is  electrical, 
the  theory  will  be  abandoned,  if  the  qualities  of  electricity  discovered 
by  experiment  fail  to  explain  the  characteristics  of  matter;  and  from 
the  nature  of  the  assumption  that  an  atom  is  an  electrically  charged 
spherical  surface  containing  negatively  charged  particles,  the  theory 
of  such  atoms  will  be  abandoned,  if  the  qualities  which  by  experi- 
ment we  know  such  an  electrically  charged  surface  containing  such 
negatively  charged  particles  would  have,  fail  to  explain  the  relation- 
ships described  by  the  periodic  law.  But  the  nature  of  the  as- 
sumption of  the  existence  of  spirits  and  their  powers  is  such  that 
the  theory  need  never  be  abandoned.  As  spirits  are  assumed  to  be 
like  nothing  in  experience,  their  powers  must  also  be  assumed,  and 
any  powers  may  be  ascribed  to  them  necessary  to  explain  any  given 
phenomena.  When  new  phenomena  are  revealed,  spirits  can  be  as- 
sumed to  have  different  or  additional  powers  and  the  theory,  there- 
fore, need  never  'be  abandoned.  The  assumption  of  Locke's  theory  ^ 
is  of  the  same  nature.  If  the  mind  is  like  nothing  in  experience,  any 
powers  may  be  ascribed  to  it,  and  any  phenomena  explained  by  it. 
So  much  for  the  distinction  between  the  use  of  assumption  in  theories 
like  the  theory  that  matter  is  electrical  and  the  theory  of  ions  and  its 
use  in  theories  like  the  theory  of  discarnate  spirits  and  the  theory  of 
mind  as  set  forth  by  Locke. 

The  theories  examined,  then,  divide  themselves  into  two  classes, 

[17] 


whether  the  basis  of  classification  is  the  nature  of  the  problem  and 
solution  or  the  method  of  procedure  employed  in  deriving  the  theory. 
From  the  point  of  view  of  the  nature  of  problem  and  solution,  we 
have  found  that  there  is  one  class  of  theories  whose  problem  is  to 
explain  the  process  of  origin  and  a  second  class  whose  problem  is  to 
reveal  the  essential  nature  of  a  thing.  From  the  point  of  view  of 
method  of  solution,  we  found  that  there  were  also  two  classes:  those 
which  proceed  by  observation  and  experiment,  a  sub-class  of  which 
makes  use  of  assumptions  in  completing  an  evidential  chain;  and 
those  which  proceed  by  making  assumptions  and  developing  the 
logical  implications  of  those  assumptions. 

A  further  examination  of  the  theories  shows  that  either  method 
of  procedure  might  be  used  with  either  class  of  problem.  Darwin's 
problem  is  one  of  origin  and  his  method  is  that  of  observation  and 
experiment;  while  Hyslop's  problem  is  also  one  of  origin  but  his 
method  that  of  assumption  and  deduction.  On  the  other  hand,  the 
problem  in  the  theory  that  matter  is  electrical  is  one  of  definition  and 
the  procedure  in  solving  it  is  that  of  observation,  and  experiment. 
While  Locke's  problem  in  his  theory  of  knowledge  is  also  one  of 
definition  but  his  method  is  That  of  assumption  and  deduction.  It 
is  evident  from  this  that  whether  the  problem  is  one  of  origin  or  one 
of  definition,  the  method  of  procedure  in  solving  it  may  be  either 
experimentation  or  assumption  and  deduction. 

Having  in  this  chapter  classified  the  theories,  and  compared  their 
problems  and  methods  of  procedure  and  discussed  the  relation  exist- 
ing between  the  two,  we  shall  continue  our  study  by  an  examination 
of  the  qualities  of  theories. 


13] 


CHAPTER   III. 

QUALITIES   OF   THEORIES. 

BELIEVABILITY  OF  THEORIES. 

An  examination  of  the  theories,  here  studied,  reveals  that  some 
have  a  much  greater  probative  force  than  others.  This  power  which 
a  theory  has  to  gain  credit  for  its  validity  may  be  called  the  be- 
lievability of  the  theory.  To  the  writer,  the  theory  of  inorganic  evo- 
lution and  Darwin's  theory  are  the  most  convincing.  A  little  less 
so  are  the  theories  of  ions  and  that  matter  is  electrical ;  while  between 
these  four  theories  and  the  theories  of  Locke  and  Hyslop  there  seems 
to  be  a  considerable  difference,  the  latter  two  theories  being  much 
less  believable. 

It  is  true  that  the  confidence  of  our  belief  in  a  theory  depends 
somewhat  upon  our  familiarity  with  it,  the  nature  of  our  education, 
and  our  general  character;  yet  it  is  equally  certain  that  there  are 
qualities  inherent  in  the  theories  themselves  which  play  by  far  the 
largest  part  in  determining  whether  the  theory  will  be  believed  or  not. 
It  is  our  purpose  here,  by  an  examination  of  the  theories,  to  reveal 
those  qualities  upon  which  believability  depends. 

We  are  convinced  by  a  brief  survey,  that  it  does  not  depend  upon 
the  nature  of  the  problem  to  be  solved  by  the  theory.  Darwin's 
theory  was  one  of  origin,  and  the  theory  of  the  electrical  nature  of 
matter  was  one  of  definition.  Both  theories  are  strongly  convincing. 
While  Hyslop's  theory,  like  Darwin's,  was  one  of  origin ;  and  Locke's 
like  the  theory  of  electrical  matter,  was  one  of  definition,  yet  neither 
Hyslop's  nor  Locke's  theory  is  of  a  believable  type. 

Believability  seems  to  have  much  more  dependence  upon  the  \ 
method  of  procedure  by  which  the  problem  is  solved.  We  have 
found  two  distinct  methods  of  procedure  exhibited  by  the  theories  in 
question,  namely:  the  method  of  experiment,  and  that  of  assumption 
and  deduction.  We  found  in  the  class  using  the  method  of  experi- 
mentation: Darwin's  theory,  the  theory  of  ions,  the  theory  of  inor- 
ganic evolutions,  and  the  theory  that  matter  is  electrical ;  while  in  the 
class  using  the  method  of  assumption  and  deduction,  we  found  Hys- 
lop's theory  and  John  Locke's.  Now  all  the  theories  of  the  first  class 
are  of  a  convincing  nature,  while  those  of  the  second  class  are  not. 
The  theories  based  upon  experimental  methods  are  the  believable  ones, 

[19] 


while  those  based  upon  assumption  and  deduction  are  comparatively 
unbelievable. 

A  close  examination  may  reveal  whether  this  relationship  is  an 
accidental  one,  in  this  case,  or  whether  it  is  a  significant  one  which  we 
may  expect  to  hold  quite  generally.  The  concepts  which  constitute 
the  essential  materials  for  Darwin's  theory  are  those  of  individual  va- 
riation, inheritance  and  natural  selection.  The  existence  of  individual 
variations,  and  their  nature  were  experimentally  investigated  by  Dar- 
win :  and  may  be  by  any  other  person.  No  one  will  doubt  that  there 
are  individual  variations.  So,  also,  the  existence  of  natural  selection, 
and  its  nature,  were  directly  investigated  by  Darwin,  and  may  be  by 
any  person  wishing  information  concerning  them.  Or  if  any  one 
doubted  either  that  individual  variations  and  inheritance  existed  or 
that  natural  selection  operated,  he  could  determine  the  facts  by  an 
investigation  of  these  forces.  The  conditions  with  regard  to  Locke's 
theory,  for  example,  are  quite  in  contrast.  Locke  did  not  examine 
the  mind  to  determine  its  properties;  he  assumed  it  to  have  a  certain 
nature.  And  upon  this  assumption  the  validity  of  his  theory  rests, 
as  we  have  shown.  The  theory  as  presented  by  Locke  offers  no  evi- 
dence for  the  validity  of  the  assumption,  and  no  evidence  exists  for 
it.  The  theory  is  in  this  peculiar  position  that  it  may  sometime  be 
shown  to  be  false,  but  never  can  be  shown  to  be  true;  for  if  the  only 
dbjects  with  which  the  mind  can  be  concerned  were  ideas,  the  mind 
itself  and  the  real  things  of  Locke's  theory  could  never  be  investigated, 
nor  the  relationships  between  them.  So  the  concepts  which  consti- 
tute Locke's  theory  have  never  been  subjected  to  experimental  investi- 
gation, but  are  purely  hypothetical;  and  the  theory  is  believable  only 
when  one  will  accept  the  unsupported  assumptions. 

The  same  contrast  maintains  between  the  theory  of  inorganic  evo- 
lution, based  upon  the  method  of  experimentation,  and  the  theory  of 
future  life  based  upon  the  method  of  assumption  and  deduction.  In 
the  theory  of  inorganic  evolution,  changes  of  temperature  are  tested 
by  instruments  which  experience  has  proved  to  be  reliable.  The  pres- 
ence or  absence  of  a  certain  element  can  be  certainly  ascertained  by 
investigating  the  light  emissions:  this  experience  has  verified.  When 
then  the  investigator,  after  a  thorough  examination,  reports  the  differ- 
ent temperatures  of  the  Sun  at  different  times,  and  the  temperature  of 
the  different  stars,  his  results  will  not  be  doubted.  Also  his  report  that 
some  elements  disappear  and  others  appear  is  the  direct  outcome  of  an 
experimental  investigation.  The  concepts  with  which  the  theory  deals 
are  experimental  entities  which  any  experimenter  may,  if  he  doubts, 
determine  the  existence  of.  If  any  of  the  things  which  the  theory 
affirms  to  exist,  did  not  exist;  or  if  the  nature  of  any  thing  was  not 

[20] 


what  the  theory  affirmed  it  to  be;  the  method  by  which  the  theory 
was  derived  makes  it  possible  to  review  its  procedure  and  correct  any 
error  in  its  determinations.  The  theory  is  for  this  reason  strongly 
believable. 

In  the  theory  of  a  future  life,  quite  different  conditions  maintain. 
We  have  shown  that  this  theory  was  derived  by  the  method  of  as- 
sumption and  deduction ;  and  that  the  strength  of  the  theory  depended 
upon  the  strength  of  the  assumptions.  If  spirits  exist  with  memories, 
power  of  rapid  motion,  power  of  communication  between  themselves 
and  between  them  and  human  beings,  then  supernormal  knowledge  is 
explained.  But  if  one  doubts  that  a  spirit  survives  the  human  body, 
that  it  can  move  without  'being  substantial,  that  it  can  see,  hear,  and 
understand  without  eyes,  ears  or  brain;  or  that  it  can  operate  the 
physical  mechanism  of  voice  production  with  all  its  intricate  muscular 
combinations,  in  the  entranced  subject;  doubt  these  assumptions  and 
the  theory  will  not  be  believed.  Now  from  the  method  by  which  the 
theory  was  derived,  these  facts  were  not  experimentally  determined. 
They  were  not  directly  investigated  by  the  author  of  the  theory  and 
no  other  person  interested  in  showing  their  truth  or  falsity  can  at 
present  investigate  them.  The  method  of  procedure  is  such  that  its 
affirmations  cannot  be  reviewed  by  methods  which  will  finally  deter- 
mine their  truth  or  falsity,  until  the  theory  is  put  upon  an  experimental 
basis,  at  which  time  it  will  no  longer  be  a  theory  of  assumption  and 
deduction.  As  the  method  by  which  the  theory  was  derived  does  not 
present  its  data  in  a  believable  state,  the  theory  does  not  carry  con- 
viction. From  this  examination  we  conclude  that  there  is  a  signifi- 
cant relationship  between  method  of  procedure  and  believability  of 
theories;  that  the  experimental  method  generally  leads  to  believable 
theories,  while  the  method  of  assumption  and  deduction  from  its 
nature  does  not. 

We  shall  also  attempt  to  show  that  believability  depends  to  some 
extent  upon  the  simplicity  of  a  theory.  However,  before  dealing 
with  this  question  it  will  be  necessary  to  consider  this  quality  of  a 
theory,  called  its  simplicity,  at  length. 

SIMPLICITY  OF  THEORIES. 

Upon  an  investigation  of  these  theories  which  we  are  here  study- 
ing, we  find  that  there  are  four  different  qualities  of  the  theories  which 
might  be  designated  by  the  term  simplicity  or  complexity.  I  shall  set 
forth  these  different  meanings  in  order. 

First,  simple  may  mean  simple  in  structure ;  the  quality  will  depend 
upon  the  number  of  concepts  in  the  theory  and  the  number  of  their 
relationships.  This  meaning  for  the  word  simple  as  applied  to  a 

[21] 


theory  is,  however,  of  little  value ;  for  the  amount  of  data  involved  in 
a  theory  has  no  significant  bearing  upon  its  important  qualities.  All 
the  theories,  here  examined,  are  simple  in  this  respect,  except,  perhaps, 
the  theory  of  ions.  Each  of  the  theories  is  made  up  of  few  concepts 
and  of  few  and  simple  relations  between  them.  Darwin's  theory  in- 
volves merely  individual  variations,  inheritance,  and  natural  selection. 
Hyslop's  deals  with  souls,  mediums,  and  communications  through  the 
mediums.  The  theory  of  inorganic  evolution  considers  merely  changes 
of  temperature  and  corresponding  changes  in  elemental  structure.  The 
theory  that  matter  is  electrical  simply  compares  the  essential  qualities 
of  electricity  and  matter.  The  theory  of  ions  is  a  little  more  complex 
in  this  respect,  involving  a  consideration  of  the  different  kinds  of  ions 
and  their  properties ;  the  number  and  arrangement  of  ions  in  the  atom ; 
and  the  relationship  between  the  structure  of  the  atom  and  its  chemical 
properties.  It  will  be  seen  that  different  as  these  theories  are  in  other 
important  respects,  they  all  contain  but  few  concepts  and  but  few 
relations  between  them,  and  are  all  in  this  sense  comparatively  simple. 

Secondly,  the  term  simple  may  be  used  to  designate  that  quality 
of  a  theory  which  depends  upon  the  directness  with  which  its  data 
can  be  presented,  and  the  number  of  other  theories  involved  in,  or 
whose  validity  is  implied  in  the  theory  in  question.  In  illustration, 
Darwin's  theory  is  simple  in  this  respect:  individual  variation,  in- 
heritance, and  natural  selection  are  processes  which  can  be  presented 
directly  in  experience.  The  theory  involves,  however,  inferences  as  to 
the  length  of  time  through  which  organic  life  has  existed  on  the  earth, 
and  the  nature  of  past  geological  conditions.  In  this  respect  the 
theory  is  in  this  second  sense  complex;  it  is  concerned  with  existences 
which  cannot  be  directly  presented  in  experience.  In  the  theory  of  in- 
organic evolution,  changes  of  temperature  on  the  earth,  sun,  and  stars 
are  inferred.  Also  the  existence  and  non-existence  of  elements  are 
inferred  from  light  emissions.  Its  materials  are  not  directly  presented 
in  experience,  and  in  this  sense  it  is  complex.  The  theory  also  in- 
volves inference  as  to  past  astronomical  changes. 

Concerning  the  theory  that  matter  is  electrical:  electrical  qualities 
are  manifestations  in  experience  and  so  also  are  the  qualities  of  mat- 
ter. But  this  theory  rests  upon  the  theory  of  ions,  the  materials  of 
which  are  inferred  existences.  This  latter  theory  deals  entirely  with 
inferred  existences.  The  ions,  their  properties  and  arrangements  are 
all  inferential  facts.  The  theory  that  matter  is  electrical  and  the 
theory  of  ions  are  both  then  comparatively  complex  in  the  sense  that 
the  materials  with  which  they  deal  are  not  facts  of  experience,  but  are 
inferences  from  it. 

Locke's  theory  and  Hyslop's  also  are  complex  in  this  sense;  and 

[22] 


peculiarly  so.  For  in  Locke*s  theory  the  mind,  ideas  as  impressions 
upon  the  mind,  and  matter  are  all  not  only  things  out  of  experience,  but 
things  like  nothing  in  experience;  things  not  to  be  inferred  from  ex- 
perience. And  in  Hyslop's  theory  the  existence  of  spirits  and  of  the 
powers  ascribed  to  them  are  not  things  which  can  be  experienced,  and 
not  things  which  can  be  inferred  from  experience.  The  materials  of 
Locke's  and  Hyslop's  theories  are  not  matters  of  experience  and  are 
like  no  things  which  are  matters  of  experience.  These  theories  are, 
therefore,  complex  in  the  sense  that  their  materials  are  not  presentable 
in  experience,  and  are  to  be  distinguished  from  the  other  theories  from 
the  fact  that  their  materials  being  like  nothing  in  experience,  are  not  to 
be  inferred  from  it.  This  latter  peculiarity  will  be  considered  under 
the  fourth  sense  of  simplicity  as  applied  to  theories. 

When  thus  applied  the  term  may  have  a  third  meaning.  It  may 
mean  only  that  the  reasonings  by  which  the  theory  is  derived  are  diffi- 
cult to  follow.  The  reasonings  may  be  sound,  but  are  intricate,  and 
thus  tax  the  strength  of  the  understanding.  However,  a  considera- 
tion of  this  sense  of  simplicity  could  have  but  little  value,  as  it  is  evi- 
dent that  the  simplicity  of  a  theory,  in  this  sense,  would  have  no  im- 
portant bearing  upon  its  other  qualities. 

There  is,  however,  a  fourth  meaning  which  simplicity  may  have 
and  which  we  shall  find  of  considerable  importance.  The  term  sim- 
plicity may  be  used  to  signify  the  intelligibility  of  a  theory,  and  com- 
plexity to  signify  unintelligibility.  A  theory  is  unintelligible,  in  whole 
or  in  part,  when  its  validity  involves  the  existence  of  things  which  we 
do  not  know  to  exist,  and  the  possibility  of  whose  existence  we  can- 
not, in  the  present  state  of  science,  understand.  An  examination  of 
the  theories  will  clarify  the  meaning  of  the  term  simplicity  as  here  used. 
Darwin's  theory  and  the  theory  of  inorganic  evolution  are  simple  in 
this  fourth  sense.  The  concepts  involved  in  both  can  be  clearly  set 
forth  to  the  understanding.  Darwin  can  present  as  facts  in  experience 
all  the  forces  which  produce  species,  and  exhibit  them  in  operation. 
And  the  astronomer  can  show  to  any  investigator  the  changes  of  tem- 
perature on  the  sun  and  in  the  stars;  and  can  show  the  elements  of 
low  atomic  weight  disappearing  and  those  of  higher  atomic  weight  ap- 
pearing as  the  temperatures  fall.  Here  the  materials  of  the  theories 
are  presented  as  determined  facts,  and  the  understanding  is  not  con- 
cerned with  contemplating  their  possibility. 

In  the  theory  of  ions  we  find  the  situation,  in  one  part  of  the 
theory,  somewhat  different.  The  conclusion  of  the  theory  is  that  the 
number  and  mechanical  arrangements  of  the  ions  in  the  atom  explain 
the  periodic  law.  But  it  is  impossible,  in  the  present  state  of  science, 
to  understand  how  chemical  quality  can  be  dependent  upon  mechan- 

[23] 


ical  structure.  If  we  knew  that  such  were  the  fact,  the  theory  of  ions 
would  not  be  concerned  with  explaining  it.  But  as  we  do  not  know  it 
to  be  a  fact,  the  theory  is  unintelligible  in  that  it  cannot  explain  to  us 
how  chemical  quality  can  be  dependent  on  mechanical  structure.  This 
theory,  however,  is  aided  in  this  aspect  by  the  fact  that  in  other  cases 
within  our  knowledge,  mechanical  structure  and  chemical  quality 
change  together.  This  gives  grounds  for  the  inference  that  a  relation- 
ship exists. 

Instances  in  which  there  are  no  grounds  for  inferring  the  existence 
of  a  fact,  and  the  possibility  of  whose  existence  cannot  be  understood, 
are  better  illustrated  by  Hyslop's  theory.  This  theory  assumes  that 
there  is  a  spirit,  which  survives  death,  with  all  the  psycho-physical 
functions  of  a  living  human  being.  From  our  experience  during  life, 
we  know  that  there  is  an  intimate  relation  between  body  and  mental 
function.  If  the  brain  is  shocked,  thinking  ceases;  if  the  auditory 
nerve  is  destroyed,  hearing  ceases;  if  the  optic  nerve  is  destroyed, 
seeing  ceases;  and  if  our  vocal  organs  are  destroyed  or  certain  brain 
cells,  speaking  ceases.  Yet  this  theory  assumes  that  after  death  the 
soul  without  brain,  eye,  ear  or  vocal  organs  performs  the  functions  of 
thought,  seeing,  hearing  and  communicating.  Now  we  do  not  know 
from  our  experience  with  spirits  that  they  have  such  powers;  as  spirits 
are  like  nothing  in  our  experience  of  which  we  have  knowledge,  we 
cannot  infer  that  they  have  such  powers;  and,  as  we  cannot  compre- 
hend how  spirits  can  perform  such  functions,  the  theory  presents  an 
unintelligibility  and  is  thus  complex  in  the  fourth  sense  above  defined. 
The  theory  presents  other  typical  instances  of  this  kind.  The  spirits 
are  assumed  to  be  present  at  almost  any  place  the  medium  chooses  to 
sit,  whether  she  has  come  to  that  place  over  railroads  or  across  seas. 
The  spirits  have  no  organs  of  locomotion  like  any  of  which  we  know 
and  therefore  their  rapid  motion  is  unintelligible  to  us.  Again,  spirits 
are  assumed  to  have  power  to  communicate  through  the  medium  with- 
out the  medium  being  conscious  of  sights,  sounds  or  touches  of  spirits ; 
and  the  theory  assumes  that  perhaps  there  is  no  use  of  the  mediums 
mental  functions  at  all;  that  the  spirit  itself  operates  the  vocal  organs 
to  produce  the  speech  of  the  medium.  We  do  not  know  these  to  be 
facts,  we  have  no  analogy  to  them;  and  as  their  possibility  cannot  be 
explained  they  are  unintelligibilities.  This  theory  then  is  found  to  be 
complex  in  the  sense  that  it  presents  many  such  incomprehensible  ele- 
ments. 

— •  In  the  same  sense  Locke's  theory  is  complex.  His  theory  in- 
volves the  conception  of  a  mind  which  is  like  an  empty  receptacle  and 
becomes  filled  with  ideas,  or  which  is  a  plastic  medium,  and  ideas  be- 
come impressed  upon  it.  But  when  Locke  speaks  of  the  mind  as 

[24] 


empty,  he  evidently  does  not  mean  spatially  empty,  and  that  ideas  are 
space  occupying  things  which  fill  it.  Yet  a  relation  between  mind  and 
ideas  is  involved  in  the  theory,  and  Locke  describes  this  relation  by 
saying  that  the  empty  is  filled.  Yet  this  emptiness  is  like  no  emptiness 
of  which  we  have  had  experience,  and  the  filling  is  like  no  filling  of 
which  we  know.  The  relationship  is,  therefore,  unintelligible.  The 
same  is  true  of  the  conception  that  ideas  are  impressed  upon  the  mind. 
Locke  here  evidently  does  not  mean  impressed  in  the  physical  sense. 
Yet  there  is  no  other  sense  of  the  word  which  we  can  conceive  of  as 
applicable.  The  theory  asserts  that  mind  and  ideas  are  intimately 
related,  but  the  relationship  is  like  no  relationship  of  which  we  have 
knowledge,  and  is,  therefore,  an  unintelligible  one. 

Locke's  theory  also  involves  the  conception  that  ideas  resemble  or 
copy  objects.  When  it  is  said  that  one  thing  resembles  another  or 
copies  it,  it  is  meant  that  the  two  are  alike  in  characteristic  respects. 
But  Locke  evidently  does  not  mean  that  the  idea  is  solid  and  extended 
like  the  object  or  that  it  possesses  any  of  the  characteristic  qualities  of 
the  object.  The  resembling  or  copying,  then,  which  Locke  refers  to, 
is  like  no  resembling  or  copying  of  which  we  know  and  is  thus  incom- 
prehensible to  us. 

This  element  of  unintelligibility  which  we  have  considered  as  a 
condition  of  complexity  in  a  theory  is  also  displayed  by  Locke's  con- 
ception of  real  knowledge.  The  theory  is  that  because  some  ideas  re- 
semble objects,  that  therefore  knowledge  concerned  with  these  ideas, 
is  knowledge  of  the  objects  themselves.  And  Locke  considers  that  we 
know  some  knowledge  to  be  real.  The  acceptance  of  the  theory  would 
necessitate  one's  believing  that  the  mind  knew  of  the  relationship  be- 
tween ideas  and  things,  although  knowledge  is  but  the  perception  of 
the  relations  between  ideas.  How  the  understanding  reaches  a  knowl- 
edge of  the  relation  between  ideas  and  things  is  to  one  accepting  the 
theory  incomprehensible.  Our  examination  of  Locke's  theory  then 
reveals  many  unintelligible  elements,  and  thus  we  shall  agree  that  the 
theory  is  complex  in  this  sense. 

It  may  be  helpful  here  to  call  attention  to  two  conditions  of  un- 
intelligibility which  the  theories  in  question  reveal,  one  of  which  makes 
the  theory  more  complex  and  the  other  does  not.  In  Darwin's 
theory,  we  know  that  individual  variations  are  inherited.  We  de- 
termine this  to  be  a  fact  by  observing  parent  and  offspring.  Yet  we 
know  little  of  the  laws  of  inheritance;  of  how  inheritance  is  accom- 
plished. This,  however,  does  not  affect  the  complexity  of  Darwin's 
theory ;  for  the  theory  needs  for  its  purposes  only  the  fact  that  there 
is  inheritance.  When  the  fact  is  known,  the  theory  is  not  concerned 
with  the  question  of  how  it  is  possible.  In  the  theory  of  ions,  how- 

[25] 


ever,  we  determined  that  the  theory  was  complex  from  the  fact  that 
the  relation  between  mechanical  structure  and  chemical  quality  was 
unintelligible.  We  do  not  know  such  a  relationship  to  be  a  fact; 
that  is  what  the  theory  invites  us  to  infer.  We  are  required  to  infer 
a  relationship,  although  at  present  the  relationship  can  in  no  way  be 
explained.  If  we  knew  that  the  relationship  existed,  we  would  not 
be  concerned  with  showing  by  what  means  it  is  accomplished.  But 
we  have  more  difficulty  in  inferring  the  relationship  to  be  a  fact,  be- 
cause the  relationship  is  at  present  unintelligible.  Hyslop's  theory 
illustrates  this  point  well.  If  we  knew  that  spirits  existed  and  could 
communicate  with  each  other  and  with  us,  the  theory  would  not  be 
concerned  with  showing  how  they  do  it.  The  existence  of  super- 
normal knowledge  could  be  explained  without  such  a  demonstration. 
But  the  theory  asks  us  to  infer  that  spirits  have  powers  of  communi- 
cation between  themselves  and  human  beings.  This  inference  is  the 
more  difficult  for  us  to  make  because  the  manner  in  which  spirits 
perform  these  functions  is  unintelligible  to  us.  A  theory  is  only 
complex  then,  when  it  asks  us  to  infer  an  unintelligible  thing  to  be  a 
fact. 

Having  considered  the  simplicity  of  the  various  theories,  we  shall 
now  study  the  relationship  between  the  method  by  which  the  theories 
were  derived,  and  their  simplicity.  We  have  found  that  simplicity 
may  mean  any  one  of  four  things.  It  may  mean  that  the  theory  has 
few  concepts  and  few  relations  between  them.  Secondly,  it  may 
mean  that  the  materials  with  which  the  theory  deals  are  things  which 
can  be  presented  in  experience,  and  not  such  as  must  be  inferred 
from  it.  Thirdly,  it  may  mean  that  the  reasonings  of  the  theory  are 
easy  to  follow.  And,  fourthly,  it  may  mean  that  the  theory  pos- 
sesses few  or  no  unintelligibilities.  Now  we  shall  find  little  relation- 
ship between  method  and  simplicity  in  the  first  three  senses.  We 
have  found  that  none  of  the  theories  here  considered  possesses  many 
concepts,  and  that,  with  the  exception  of  the  theory  of  ions,  their 
reasonings  are  easy  to  follow.  Yet  Locke's  and  Hyslop's  theories 
are  derived  by  the  method  of  assumption  and  Darwin's  theory,  the 
theory  of  inorganic  evolution,  and  the  theory  that  matter  is  electrical 
are  based  upon  the  experimental  method.  It  is  very  evident  that 
the  method  of  assumption  might  lead  to  a  theory  complex  in  struc- 
ture, and  containing  difficult  reasonings  by  increasing  the  number  of 
assumptions  and  the  intricacy  of  their  implications.  And  so  the  ex- 
perimental method  may  lead  to  a  theory  involving  many  concepts  and 
difficult  reasonings.  The  theory  of  ions  is  such  a  theory.  The  con- 
ceptions involved  in  it  are  comparatively  numerous.  It  involves  the 
conception  that  matter  is  made  up  of  ions  of  different  kinds;  that 

[26] 


these  ions,  in  different  numbers  and  with  different  arrangements  form 
the  atom;  that  the  difference  of  number  and  arrangement  of  the  ions 
in  the  atom,  conditions  the  difference  of  qualities  expressed  by  the 
Periodic  Law.  The  mathematical  reasonings  involved  in  the  theory 
determining  the  number  of  ions  in  different  atoms,  and  the  causes  of 
instability  of  certain  atoms  are  very  difficult.  Thus  it  is  evident  from 
our  examination  that  either  method  of  procedure  may  give  rise  to 
complex  theories;  complex  'from  the  point  of  view  of  structure  and 
difficulty  of  reasoning. 

So  also  the  experimental  method  may  give  rise  either  to  a  simple 
theory,  simple  meaning  one  whose  materials  can  be  directly  pre- 
sented in  experience;  or  to  a  complex  theory,  a  complex  theory  being 
one  whose  materials  cannot  be  presented  in  experience.  Darwin's 
theory  we  found  to  be  simple  in  this  respect;  individual  variations, 
inheritance,  and  natural  selection  being  processes  subject  to  direct 
observation:  while  the  theory  of  ions,  we  found  to  be  complex  in  this 
respect;  the  ions  and  their  combinations  being  inferred  existences. 
Both  theories  were  derived  by  the  experimental  method. 

The  method  of  assumption  and  deduction,  however,  will  always 
give  rise  to  a  theory  complex  in  this  respect;  for  the  assumption  is  al- 
ways of  the  existence  or  of  the  qualities  of  something  out  of  experi- 
ence. This  is  shown  by  both  Hyslop's  and  Locke's  theories.  Hys- 
lop's  theory  assumes  spirits  with  certain  powers  to  exist  out  of  expe- 
rience, and  Locke's  theory  assumes  minds,  impressions  upon  minds, 
and  "real  things"  to  exist,  although  never  observed.  Thus  a  theory 
derived  by  experiment  may  be  either  simple  or  complex  in  this  respect ; 
that  is,  its  materials  may  be  either  observed  existences  or  inferred 
existences;  while  a  theory  derived  by  the  method  of  assumption,  will 
always  be  complex  in  this  respect ;  that  is,  its  materials  will  always  be 
in  whole  or  in  part,  existences  beyond  experience. 

It  remains  to  consider  the  relation  between  method  of  procedure 
and  simplicity  in  the  fourth  sense,  in  which  it  was  defined  to  mean  free 
from  unintefligibilities.  The  theory  of  ions,  we  found  to  be  a  theory 
based  upon  experimentation,  while  Hyslop's  was  found  to  be  based 
upon  the  method  of  assumption  and  deduction.  Yet  both  theories 
contain  unintelligible  elements.  It  is  evident  that  a  theory  may  be 
complex,  in  the  sense  that  it  contains  unintelligible  elements,  by  which- 
ever method  it  is  derived.  This  will  be  obvious  when  we  consider 
the  source  of  unintelligibilities.  Things  are  unintelligible  in  the  sense 
of  the  word  as  here  used,  only  because  we  do  not  know  enough  about 
them.  As  knowledge  is  gained,  primarily  by  observation  and  experi- 
ment, it  may  be  said  that  unintelligibilities  arise  when  observation  and 
experiment  are  incomplete.  In  the  theory  of  ions  sufficient  investigation 

[27] 


may  clearly  show  the  relation  between  mechanical  structure  and 
chemical  quality.  And  in  Hyslop's  theory,  sufficient  observation  and 
experiment  may  reveal  the  nature  of  death,  and  the  powers  of  spirits, 
if  such  are  found  to  exist.  It  is  evident  that  such  uninvestigated  parts 
may  occur  in  a  theory  developed  by  either  method  of  procedure. 
However,  our  investigation  has  revealed  that  by  far  the  most  unin- 
telligibilities  of  this  kind  occurred  in  the  theories  of  Locke  and  Hyslop, 
both  of  which  are  based  upon  the  method  of  assumption  and  deduction. 
A  further  examination  of  those  theories  may  reveal  the  reason  for  this. 
Both  theories  assume  the  existence  out  of  experience  of  something,  like 
nothing  in  experience.  This  necessitates  additional  assumptions  as  to 
all  the  qualities  of  the  thing  assumed  to  exist  out  of  experience.  Being 
like  nothing  in  experience,  we  cannot  comprehend  its  nature,  nor  how 
it  exercises  the  powers  ascribed  to  it.  Hence  the  great  unintelligibility 
of  these  theories.  We  cannot  comprehend  the  nature  of  the  spirit  con- 
ceived of  in  Hyslop's  theory.  Spirits  communicate  but  have  no  means 
of  communication  of  which  we  have  knowledge.  They  move  rapidly 
but  have  no  means  of  locomotion  like  any  with  which  we  are  familiar. 
Thus  each  of  the  powers  ascribed  to  them  is  unintelligible  to  us. 

So  in  Locke's  theory,  the  mind  is  out  of  experience  and  is  like 
nothing  in  experience.  We  cannot  therefore  comprehend  its  nature. 
The  mind  is  impressed  in  a  different  way  from  any  we  have  knowledge 
of.  The  idea  resembles  the  object  with  a  different  kind  of  resem- 
blance from  any  of  which  we  have  had  experience.  So  the  thinker  in 
dealing  with  Locke's  theory  meets  with  these  many  incomprehensible 
elements  and  finds  the  theory  in  this  sense  complex.  This  evidently 
is  a  necessary  consequence  of  applying  the  method  of  assumption  as 
it  is  applied  by  Locke  and  Hyslop.  Assumptions  may  be  made  of 
the  existence  of  things  out  of  experience  without  incurring  incompre- 
hensible elements.  In  the  theory  of  ions,  it  is  assumed  that  the  atom 
is  constituted  of  a  spherical  shell  of  positive  electrification  surround- 
ing the  negatively  charged  ions.  Now  a  spherical  surface  of  electrifi- 
cation is  a  thing  producible  in  experience;  a  thing  which  can  be  in- 
vestigated and  whose  qualities  we  therefore  know.  The  assumption 
is  not  here,  as  in  the  theories  of  Locke  and  Hyslop,  of  a  thing  out  of 
experience  like  nothing  in  experience,  and  further  assumptions  as  to  its 
qualities  are  not  necessitated.  When  such  an  assumption  is  made,  un- 
intelligibilities  do  not  arise;  for  the  powers  of  the  thing  assumed  are 
known  from  experiment.  Whereas,  when  the  method  of  assumption 
is  applied  as  in  the  theories  of  Locke  and  Hyslop,  and  a  thing  is 
assumed  to  exist  like  nothing  in  our  experience,  then  we  know  nothing 
of  that  thing  or  its  qualities  from  experience,  and  must  assume  it  to 
have  certain  qualities,  although  we  cannot  understand  its  possession  of 

[28] 


them.  Thus  we  conclude  that  the  method  of  assumption,  as  revealed 
in  the  theories  of  Locke  and  Hyslop,  will  inevitably  give  rise  to  a 
theory  complex  because  it  possesses  unintelligible  elements. 

Having  now  fully  considered  the  question  of  simplicity  of  theories, 
we  shall  return  to  the  question  of  the  relation  between  believability  of 
theories  and  their  simplicity.  It  will  need  no  discussion  to  show  that 
simplicity  has  no  bearing  upon  believability,  when  we  mean  by  sim- 
plicity only  that  the  theory  has  a  few  concepts  simply  related;  or  that 
the  theory  possesses  no  difficult  reasonings.  The  theory  of  inorganic 
evolution  is  simple  in  both  these  respects  and  is  a  very  believable 
theory.  Hyslop's  theory  is  also  very  simple  in  both  these  respects, 
but  is  not  a  believable  theory.  While  the  theory  of  ions  is  compara- 
tively complex  in  these  two  respects  and  it  is  a  believable  theory. 
Darwin's  theory  and  the  theory  that  matter  is  electrical  are  simple  in 
these  respects  and  are  both  believable;  while  Locke's  theory,  also 
simple  in  these  respects,  is  not  convincing.  It  is  evident  that  theories 
simple  in  structure  and  easy  to  understand  in  their  reasonings,  may  or 
may  not  be  believable ;  that  there  is  no  apparent  relation  between  sim- 
plicity so  understood  and  believability.  Is  there  any  relation  between 
simplicity  in  the  sense  of  presentable  in  experience  as  contrasted  with 
inferred  from  experience,  and  believability?  Darwin's  theory  is  the 
most  simple  of  all  the  theories  examined  in  this  respect  and  is  also  the 
most  believable.  In  the  theory  of  ions,  the  ions  and  their  relationships 
are  inferred  existences,  and  although  the  theory  is  very  believable,  yet 
just  because  there  is  room  to  doubt  the  existence  of  ions  and  their  re- 
lationships, the  theory  is  less  believable  than  Darwin's.  In  the  theory 
of  inorganic  evolution  changes  of  temperature  on  the  sun  and  stars  are 
inferred  existences,  and  also  the  appearance  and  disappearance  of  ele- 
ments in  those  places;  yet  the  methods  by  which  those  conditions  are 
discovered  have  been  so  thoroughly  tested  that  the  evidence  leaves  no 
doubt  in  the  mind,  and  a  theory  results  quite  as  believable  as  Dar- 
win's theory,  although  in  the  theory  of  inorganic  evolution  the  materials 
of  the  theory  are  inferred  existences.  It  is  evident  that  where  part  or 
all  of  the  data  with  which  a  theory  is  concerned  is  inferred  existence, 
that  the  believability  of  the  theory  will  be  somewhat  affected  by  the 
strength  of  the  inference  of  the  existence.  And  that  theory  which  is 
most  simple  in  this  respect,  whose  materials  are  for  the  most  part  ex- 
perienced facts,  will  be  the  most  believable,  other  conditions  being  the 
same. 

It  remains  to  consider  the  relation  between  believability  and  sim- 
plicity in  the  fourth  sense,  where  it  was  denned  to  mean  freedom  from 
unintelligible  elements.  The  most  believable  theories  considered,  the 

[29] 


theory  of  inorganic  evolution  and  Darwin's  theory,  are  free  from  un- 
intelligible elements. 

We  have  noted  that  the  theory  of  ions  had  involved  in  its  reasoning 
one  unintelligible  element;  that  the  dependence  of  chemical  quality 
upon  the  mechanical  structure  of  the  atom  was  not  known  to  be  a 
fact  and  in  the  present  state  of  science  is  unexplainable.  It  is  evident 
that  this  impairs  the  believability  of  the  theory.  In  order  to  believe 
the  theory,  we  must  infer  that  chemical  quality  is  dependent  upon  me- 
chanical structure,  and  this  is  the  more  difficult  to  do  just  because  we 
cannot  explain  such  a  relationship.  However,  the  theories  most  com- 
plex in  this  respect,  the  theories  possessing  the  most  unintelligible  ele- 
ments, were  the  theories  of  Locke  and  Hyslop.  These  two  were  also 
the  least  believable  of  the  theories  examined.  In  dealing  with  the 
question  of  the  relation  between  method  of  procedure  and  believability, 
we  discovered  that  the  method  of  assumption  gave  rise  to  unintelligible 
elements  in  these  theories,  and  that  because  of  these  elements  the 
theories  lacked  believability.  It  will,  therefore,  be  unnecessary  to  show 
here  that  theories,  complex  in  this  respect,  will  lack  believability.  It 
will  hardly  be  disputed  that  when  a  theory  requires  an  inference  to  be 
made,  that  inference  will  be  less  readily  made,  when  it  is  of  the  ex- 
istence of  unintelligible  things.  The  theories  possessing  most  such  in- 
comprehensible elements,  like  the  theories  of  Locke  and  Hyslop,  are 
the  least  believable.  Therefore,  we  conclude  that  there  is  an  inti- 
mate relationship  between  the  believability  of  a  theory  and  its  com- 
plexity, when  complexity  refers  to  the  existence  of  unintelligible  ele- 
ments. 

THE  VERIFIABILITY  OF  THEORIES. 

To  verify  means  to  show  the  truth  of.  We  shall  first  consider  the 
question  of  how  theories  are  verified  and  on  what  their  verifiability  de- 
pends. We  have  found  that  there  are  two  distinct  types  of  theories; 
those  of  definition  and  those  of  origin.  How  are  theories  of  definition 
verified?  The  theory  that  matter  is  electrical  is  a  theory  of  definition, 
and  we  shall  consider  how  its  truth  may  be  shown.  We  can  deter- 
mine by  observation  and  experiment  the  essential  qualities  of  elec- 
tricity. To  demonstrate  that  matter  is  electrical,  we  must  show  that 
it  has  the  same  essential  qualities  as  electricity.  An  investigation  of 
matter  will  reveal  its  qualities,  and  they  can  then  be  compared  with 
those  of  electricity.  The  characteristic  quality  of  matter  is  found  to  be 
inertia.  By  experiment  we  show  that  electricity  possesses  this  same 
quality.  Therefore,  electricity  is  matter,  or  matter  is  electricity. 
Here  then,  we  see  that  verification  consists  in  showing  that  the  facts 
affirmed  by  the  theory  are  true  by  experimentally  manifesting  them  in 
experience,  or  gaining  evidence  for  their  existence.  Once  the  theory 

[30] 


is  set  forth,  all  evidence  adding  to  the  strength  of  its  inferences,  is  a 
verification  of  it ;  for  the  facts  of  evidence  were  implied  to  exist  by  the 
theory,  they  being  merely  the  manifestations  of  the  thing  which  the 
theory  affirms  to  exist.  The  verification  of  a  theory  of  definition,  then, 
consists  in  revealing  the  facts  affirmed  by  it  in  experience ;  or  the  im- 
plications of  those  facts. 

How  are  theories  of  origin  verified?  Darwin's  theory  is  a  theory 
of  origin.  The  conclusion  drawn  in  the  theory  is  that  species  origi- 
nated by  virtue  of  individual  variations,  inheritance,  and  natural  selec- 
tion. Here,  we  cannot  directly  show  this  to  be  true  by  reproducing  the 
past  history  of  organic  life,  as  we  did  show  matter  to  be  electrical  by 
having  it  manifest  the  qualities  of  electricity.  We  can,  however,  show 
by  experiment  that  individual  variations,  inheritance,  and  selection 
will  produce  species.  We  can  exhibit  this  fact  in  experience.  But 
the  further  verification  of  the  theory  requires  us  to  show  that  these 
forces  did  actually  so  operate  in  the  past  as  to  produce  present 
species.  If  this  was  a  fact,  certain  things  are  implied  to  be  true  in 
the  present,  and  the  verification  of  the  theory  will  consist  in  revealing 
in  experience  the  truth  of  these  implications.  If  the  forces  of  evolution 
have  so  operated  in  the  past,  the  remains  of  organic  life  will,  where 
preserved,  show  the  gradual  variation  in  type,  fitting  the  succeeding 
generations  better  for  life.  When  such  conditions  of  the  remains  of 
organic  life  are  shown,  the  validity  of  the  theory  is  to  some  extent  evi- 
denced or  verified.  Thus  the  verification  of  a  theory,  whether  it  be 
one  of  definition  or  of  origin,  consists  in  revealing  in  experience  the 
facts  affirmed  by  the  theory  to  be  true;  or  the  implications  of  those 
facts.  Therefore,  in  so  far  as  the  materials  of  a  theory  can  be  sub- 
jected to  observation  or  experiment,  the  theory  is  verifiable.  Either  the 
facts  affirmed  by  the  theory  must  be  revealed,  or  the  implications  made 
manifest.  Those  theories  founded  upon  the  experimental  method  have 
already  revealed  many  of  the  implications  of  the  facts  inferred,  in  the 
evidence  gathered  for  the  theory.  All  that  stands  in  the  way  of  fur- 
ther verifying  such  theories  is  the  improvement  of  the  facilities  for  ex- 
perimenting, and  the  application  of  these  facilities. 

Experiment  will  also  be  the  method  of  verifying  theories  which 
make  use  of  assumptions.  The  theory  of  ions  assumes  the  atom  to  be 
constructed  in  a  certain  way.  The  theory  can  be  verified  in  this  re- 
spect by  showing  that  the  implications  of  this  assumption  are  true. 
If  this  assumption  is  true,  the  atomic  weights  of  atoms  will  change 
in  accordance  with  a  certain  law.  By  experiment,  it  is  shown  that  the 
atomic  weights  do  change  according  to  that  law.  In  this  way  the  as- 
sumption is  to  a  certain  extent  verified.  The  assumption  may  be  fur- 
ther verified  either  by  a  direct  examination  of  the  atom,  if  that  be- 

[31] 


comes  possible,  or  by  further  showing  the  implications  of  the  assump- 
tion to  be  true.  The  theory  of  ions  also  involves  the  inference  that 
changes  in  mechanical  structure  give  rise  to  changes  in  chemical  qual- 
ity. This  inference  could  be  verified  by  changing  the  mechanical 
structure  of  atoms  in  our  laboratories  and  noting  the  consequent 
changes  of  chemical  qualities ;  or  by  finding  numerous  instances  where 
there  are  with  differences  of  mechanical  structure,  corresponding  dif- 
ferences of  chemical  quality.  Thus  we  conclude  that  where  a  theory 
is  based  upon  the  experimental  method,  the  difficulties  in  verifying  it 
are  simply  the  difficulties  in  the  way  of  further  observation  and  experi- 
ment. 

We,  however,  meet  with  peculiar  conditions  of  verification  in  the 
theories  based  upon  the  method  of  assumption  and  deduction.  In 
Hyslop's  theory  the  existence  of  spirits  and  their  qualities  are  assumed. 
The  theory  can  be  verified  by  revealing  the  existence  of  spirits  by 
presenting  them,  if  possible,  in  experience;  or  by  gathering  evidences  of 
their  existence  from  experiments.  The  peculiarity  which  one  finds  in 
the  verification  of  this  theory  is  that  in  order  to  verify  it,  the  spirits 
themselves  must  be  subjected  to  direct  investigation.  Being  like  no 
other  things  of  which  we  know,  we  cannot  investigate  other  things  and 
apply  our  conclusions  to  spirits  by  analogy.  Contrast  the  conditions  of 
verification  in  the  theory  of  ions.  The  inference  there  is  that  an  ion 
is  an  electrically  charged  particle.  Now  we  can  experiment  with 
electrically  charged  particles  and  can  find  what  their  properties  are, 
even  though  we  cannot  experiment  directly  with  an  ion.  In  the  case 
of  spirits,  however,  we  have  nothing  like  them  in  experience  which  we 
can  investigate;  and  therefore  the  theory  is  to  be  verified  only  by  di- 
rectly investigating  spirits  themselves.  Until  spirits  have  been  di- 
rectly investigated,  and  we  know  what  they  are  like,  we  cannot  infer 
their  existence  from  any  occurrences  in  experience,  because  we  can- 
not know  until  then,  that  the  occurrences  are  such  as  spirits  are  able 
to  produce. 

The  same  situation  presents  itself  when  we  attempt  to  verify 
Locke's  theory.  /  Locke  assumes  that  the  mind  is  a  plastic  medium  and 
that  ideas  are  impressed  upon  it  by  operations  of  matter.  This,  we 
could  verify  by  producing,  if  that  were  possible,  an  idea  experimentally 
in  that  way.  We  can  verify  this  assumption  in  no  other  way.  The 
mind  is  like  nothing  in  our  experience,  and  we  therefore  cannot  deter- 
mine by  analogy  what  its  qualities  are.  When  therefore  an  idea  oc- 
curs, we  cannot  say  it  was  conditioned  by  an  impression  upon  a  mind ; 
for  we  do  not  know  whether  there  is  a  substance  which  when  im- 
pressed will  give  rise  to  an  idea.  We  must  impress  something  ,and 
thus  produce  an  idea  before  we  can  know  that  impressions  of  sub- 

[32] 


tances  are  ideas.  In  order,  therefore,  to  verify  Locke's  theory,  the 
mind  itself  must  be  directly  investigated.  We  discover,  then,  that  the 
theories  based  upon  the  method  of  assumption  and  deduction  are  pe- 
culiar in  this  respect,  that  their  verification  requires  a  direct  investiga- 
tion of  the  thing  assumed  to  exist.  No  inference  can  be  made  con- 
cerning the  assumed  objects,  until  their  qualities  are  known.  It  is 
notable  that  in  order  to  verify  these  theories,  they  must  be  given  a  foun- 
dation in  experiment  and  that  when  verified  they  will  no  longer  be 
theories  of  assumption  and  deduction.  If  this  conclusion  is  sound, 
we  can  further  affirm  that  there  is  only  one  method  by  which  a  veri- 
fied theory  can  be  reached ;  for  we  found  from  our  investigation  that 
there  were  only  two  principal  methods  of  theorizing:  the  method 
based  upon  assumption  and  deduction  and  that  based  upon  observa- 
tion and  experiment. 

We  conclude  then  that  whether  a  theory  is  based  upon  the 
method  of  experiment  or  upon  the  method  of  assumption,  it  is  verifi- 
able in  so  far  as  its  materials  are  subject  to  experimental  investiga- 
tion. And,  considering  the  theories  which  we  have  thus  far  investi- 
gated, there  are  none  but  what  we  can  hope  in  time  to  verify  or  dis- 
prove experimentally.  The  individual  variations,  inheritance,  and 
natural  selection  of  Darwin's  theory;  the  ions  and  their  properties  in 
the  theory  of  ions;  the  changes  of  temperature  and  elemental  struc- 
ture in  the  theory  of  inorganic  evolution ;  and  the  inertia  of  matter  and 
properties  of  electricity  in  the  theory  that  matter  is  electrical,  have  all 
been  to  some  extent  investigated,  and  apparently  nothing  prevents  their 
being  investigated  in  greater  detail.  In  Hyslop's  theory  the  spirits 
have  not  been  experimentally  investigated;  but  if  spirits  exist,  we  can 
hope  by  experiment  to  discover  their  existence  and  properties;  and  if 
they  do  not  exist  we  can  hope  to  explain  super-normal  knowledge 
without  assumptions  concerning  them.  So  in  Locke's  theory,  the 
mind  which  Locke  assumed  has  not  been  revealed  by  experiment;  but 
if  it  exists  there  is  no  reason  to  doubt  but  that  it  may  be;  or,  if  it  does 
not  exist  we  can  hope  to  explain  ideas  and  knowledge  in  some  other 
way. 

If  then  our  investigation  covered  all  types  of  theories,  we  could 
conclude  that  all  theories  are  verifiable  and  that  there  is  only  a  ques- 
tion of  more  or  less  difficulty  in  verification.  We  cannot,  however, 
securely  draw  this  conclusion  until  we  have  investigated  a  type  of 
theories  which  Imanuel  Kant  affirmed  to  be  true  a  priori,  prior  to  and 
independent  of  all  experience.  Poincare  has  recently  called  the  same 
type  of  theories  conventions,  neither  true  nor  false;  suggested  by  ex- 
perience but  not  of  a  nature  to  be  verified  in  it.  Among  such  theories 
are  those,  that  there  are  lines  which  never  meet,  however  far  pro- 

[33] 


duced;  that  matter  is  indestructible;  that  energy  in  its  various  transfor- 
mations is  constant  in  quantity ;  that  action  and  reaction  are  equal,  but 
in  opposite  directions ;  and  that  a  body  subjected  to  no  force  will  move 
continuously  with  uniform  velocity  in  a  straight  line.  I  shall  take  the 
last  mentioned  theory  as  representative  of  the  class.  We  shall  con- 
sider the  question,  then;  can  the  theory  that  a  body  subjected  to  no 
force  will  move  continuously  in  a  straight  line,  be  verified?  We  can- 
not withdraw  a  body  from  the  action  of  every  force,  argues  Poin- 
care,  at  least  we  should  not  know  that  we  had  done  so.  An  experi- 
mental law  is  subject  to  revision,  but  this  law  may  be  extended  to  the 
most  general  cases;  for  in  these  cases  experiment  is  neither  able  to 
confirm  or  contradict  it. 

Now  we  first  note  that  this  theory  deals  with  bodies,  forces  and 
directions  of  motion;  all  of  which  are  subjects  capable  of  experi- 
mental investigation.  By  experiment  the  conditions  giving  rise  to 
forces  can  be  ascertained.  A  moving  body  is  a  thing  of  our  expe- 
rience, and  its  direction  of  motion  can  be  investigated.  Apparently 
then,  all  the  materials  of  the  theory  are  capable  of  experimental  in- 
vestigation. As  the  conditions  giving  rise  to  forces  are  known,  we  can 
ascertain  what  forces  are  acting  upon  a  body.  As  its  direction  of 
motion  is  a  thing  of  experience,  we  can  determine  whether  the  motion 
is  straight  or  variable.  The  theory,  however,  makes  an  affirmation 
concerning  a  body  acted  on  by  no  force,  and  such  a  body  we  cannot 
present  in  experience.  We  can,  however,  make  inferences  concerning 
such  a  body,  and  if  those  inferences  have  an  experimental  foundation, 
the  theory  is  in  so  far  verified,  or  may  be.  Although  we  cannot  re- 
move from  the  body  all  forces  acting  upon  it,  we  can  determine  the 
effect  of  those  forces  which  continue  to  act  upon  it;  and  can  infer  in 
what  condition  the  body  would  be  without  the  action  of  those  forces. 
However,  it  is  urged,  that  we  cannot  know  certainly  but  that  some 
force  is  acting  which  has  escaped  our  notice,  or  which  is  of  a  mys- 
terious nature.  This  is  true,  and  is,  I  understand,  the  reason  why 
the  law  of  inertia  is  a  theory,  is  problematical,  and  not  a  fact.  It 
cannot  be  known  positively  to  be  true  because  we  cannot  give  an  ex- 
hibition of  the  law  in  experience  and  be  certain  that  ideal  conditions 
maintain.  Neither  can  it  ever  be  known  absolutely  to  be  false;  for  if 
a  body  moves  with  unexplainable  irregularity,  we  cannot  be  certain 
but  that  some  unknown  force  is  acting  upon  it.  However,  we  might 
infer  that  the  law  is  false,  and  verify  our  inference  to  a  certain  extent 
by  experiment;  just  as  we  infer  it  to  be  true.  We  infer,  because  facts 
cannot  be  fully  revealed  in  experience;  and  for  the  same  reason,  in- 
ferences are  always  more  or  less  uncertain.  A  verification  is  not  an 
actual  display  of  the  facts  inferred  by  the  theory,  in  experience;  if  it 

[34] 


were,  the  inference  would  cease  to  be  and  fact  would  exist  in  its 
stead.  In  the  case  of  the  ultimate  inferences  of  science,  we  act  upon 
them  with  great  confidence,  not  because  they  cannot  be  shown  cer- 
tainly to  be  true  or  false,  but  because  experiment  has  so  far  strength- 
ened the  inference  of  their  validity.  Between  the  spheres  of  fact  and 
pure  assumption  or  convention,  lies  the  scale  of  inferences  more  and 
less  certain;  and  because  a  theory  is  not  a  certainty,  we  cannot  con- 
clude therefore  that  it  is  a  mere  convention:  it  may  be  an  inference  to 
a  greater  or  less  extent  verifiable.  If  I  am  justified  in  considering  the 
law  of  inertia  as  typical  of  ultimate  scientific  inferences,  we  can  con- 
clude that  the  so-called  a  priori  truths  or  conventions  are  inferences 
based  upon  and  to  a  great  extent  verifiable  in  experience. 

We  conclude  then,  from  our  examination  of  the  verifiability  of 
theories,  that  theories  are  verifiable  in  so  far  as  the  grounds  upon 
which  their  inferences  are  based  are  subject  to  experimental  investiga- 
tion ;  and  it  matters  not  what  the  problem  involved  in  the  theory  may 
be,  or  what  its  method  of  procedure  in  solution. 

From  the  fact  that  verification  is  defined  to  be  the  showing  of  the 
truth  of  a  theory,  the  relation  between  verification  and  believability  of 
theories  is  manifest.  We  have  already  discovered  in  our  study  that 
those  theories  for  which  there  is  the  most  experimental  evidence,  which 
are  most  verified;  Darwin's  theory,  The  Theory  of  Ions,  and  the 
theory  of  Inorganic  Evolution,  are  the  most  believable;  while  those 
theories  which  were  not  founded  upon  experiment  were  not  verified  and 
were  difficult  of  verification,  were  the  least  believable  theories.  Be- 
lieva'bility  increases  in  proportion  as  verification  approaches  complete- 
ness. 

MEANING  OF  TRUTH  OF  A  THEORY. 

We  defined  verification  to  be  the  showing  of  the  truth  of  a  theory. 
We  shall  consider  now  what  is  meant  by  the  truth  or  falsity  of  a  hypo- 
thesis. It  has  been  considered,  on  one  side,  that  the  propofitions 
which  a  theory  asserts  are  either  true  or  false  from  the  moment  they 
are  asserted;  while,  on  the  other  side,  it  is  conceived  that  theories  are 
not,  when  proposed,  true  or  false,  but  are  made  so  by  the  success  or 
failure  of  verification.  The  former  view  is  that  verification  shows  the 
truth  of  a  theory;  the  latter  that  verification  makes  the  truth  of  a 
theory.  According  to  one  view,  at  the  time  Darwin  first  affirmed 
that  species  originated  by  natural  selection,  that  theory  was  either 
true  or  false,  even  though  entirely  unconfirmed  or  unrefuted;  that 
the  conditions  of  the  origin  of  species  existed  at  that  time  and  either 
did  or  did  not  correspond  with  Darwin's  Statement.  While,  accord- 
ing to  the  second  conception  of  truth,  Darwin's  statement  before  it 

[35] 


was  confirmed  and  believed,  was  neither  true  nor  false,  and  only 
became  true  as  evidence  added  to  its  strength  and  believability ;  that 
when  the  proposition  was  first  announced,  there  was  no  knowledge 
state  in  which  species  represented  themselves  to  have  originated  in  the 
ascribed  manner;  that  therefore  the  proposition  was  sterile,  and  only 
as  actual  knowledge  states  developed  in  which  species  actually  implied 
an  origin  in  the  affirmed  manner,  did  the  proposition  become  vital  and 
true. 

It  is  worthy  of  note  that  whichever  view  one  adopts  concerning  the 
nature  of  truth,  the  practical  consequences  will  be  the  same.  One 
will  confirm  his  theories  in  the  same  way,  he  will  consider  it  confirmed 
to  the  same  extent  and  at  the  same  time ;  he  will  receive  and  reject  the 
same  theories;  and  the  system  of  required  knowledge  will  be  the  same 
to  him.  Only,  one  school  will  insist  that  a  true  theory  was  true  and  a 
false  theory  was  false  from  the  time  they  were  asserted  as  proposi- 
tions; while  the  other  school  will  insist  that  a  theory  was  only  true  or 
false  from  the  time  and  to  the  extent  that  its  truth  or  falsity  was  be- 
lieved in  or  appreciated.  So  far  as  practice  is  concerned,  one  may 
choose  either  conception  of  truth;  his  choice  will  have  no  influence 
upon  his  manner  of  dealing  with  theories;  neither  upon  their  origin 
nor  upon  their  usefulness. 

IN  WHAT  SENSE  Do  THEORIES  EXPLAIN. 

In  connection  with  the  question  of  the  truth  and  falsity  of  theories, 
I  shall  consider  the  question  of  how  far  do  theories  explain;  for  we 
should  hardly  believe  that  a  theory  would  be  considered  true  or  be 
believed  in,  which  did  not  explain  the  phenomena  in  question.  Our 
research  has  revealed  two  distinct  kinds  of  problems  and  two  corre- 
sponding kinds  of  explanations  or  solutions.  Where  the  problem  was 
one  of  definition,  as  in  the  theory  that  matter  is  electrical,  an  explana- 
tion was  made  by  finding  the  identity  of  essential  qualities  in  matter 
and  electricity;  and  where  the  problem  was  one  of  origin,  as  in  Dar- 
win's "Origin  of  Species,"  an  explanation  was  made  by  revealing  the 
conditions  under  which  species  originated.  These  were  the  only  two 
kinds  of  explanation  attempted  by  any  of  the  thinkers  whom  we  have 
studied.  No  attempt  was  made  in  the  theory  that  matter  is  electrical 
to  determine  why  electricity  attracts,  or  what  the  essential  nature  of  at- 
traction is;  and  no  attempt  was  made  by  Darwin  to  show  why  indi- 
viduals vary  or  why  inheritance  operates.  In  none  of  the  theories  was 
an  attempt  made  to  arrive  at  final  essences  or  final  causes ;  and  so  our 
study  justifies  us  in  saying  that  the  explanation  which  thinkers  succeed 
in  making  involve  no  such  determinations.  Until  then  investigation 
reveals  a  different  kind  and  a  more  final  explanation,  we  shall  consider 

[36] 


Ahat  phenomena  are  fully  explained  either  where  their  qualities  are 
revealed  or  the  conditions  of  their  origin  made  manifest. 

USEFULNESS  OF  THEORIES. 

Having  considered  the  simplicity,  believability  and  verifiability  of 
theories  in  relation  to  the  method  by  which  they  were  produced,  we 
shall  next  consider  the  bearing  of  these  qualities  upon  the  usefulness 
of  theories.  And  the  first  essential  to  a  theory  being  useful  is  that  it  be 
believable ;  for  until  a  theory  is  believed  in,  it  will  not  be  acted  upon. 
Those  theories  which  we  found  to  be  most  verified  and  thus  most  be- 
lievable: Darwin's  theory,  the  theory  of  Ions,  and  the  theory  of  in- 
organic evolution,  we  shall  expect  to  find  among  the  useful  theories; 
and  those  which  have  not  been  verified,  we  shall  expect  to  find  of  little 
use.  Our  investigation  has  revealed  that  experimental  methods  gave 
rise  to  verifiable  and  believable  theories  and  that  the  method  of  as- 
sumption gave  rise  to  theories,  difficult  of  verification  and  to  a  small 
degree  believable.  Thus  there  appears  a  close  relationship  between 
the  utility  of  a  theory  and  the  method  by  which  it  was  derived.  This 
will  more  fully  appear  when  we  consider  the  dependence  of  utility 
upon  other  qualities  of  theories,  which  bear  a  close  relationship  to 
method  of  procedure.  We  discovered  that  those  theories  which  were 
most  complex,  in  the  sense  that  they  contained  most  incomprehensible 
elements,  were  the  least  believable ;  and  that  this  quality  of  complexity 
was  a  direct  result  of  the  use  of  the  method  of  assumption  and  deduc- 
tion as  applied  by  Locke  and  Hyslop.  We  also  found  that  theories 
derived  by  this  method  were  most  difficult  of  verification  because  we 
could  infer  nothing  concerning  the  assumed  objects  out  of  experience 
until  we  had  directly  investigated  their  natures.  Being  difficult  of  veri- 
fication, they  can  gain  belief  slowly,  if  at  all,  and  until  they  have  been 
to  some  extent  verified  and  have  gained  belief,  they  of  course  will  re- 
main useless  in  the  spheres  of  practice  and  thought. 

Our  investigation  has  revealed  that  the  method  of  assumption  and 
deduction  gives  rise  to  theories  complex  in  the  sense  of  containing  in- 
comprehensible elements;  difficult  of  verification  because  they  assume 
the  existence  of  things  out  of  experience  like  no  things  in  experience; 
unbelievable  because  no  evidence  is  offered  for  the  existence  of  the  as- 
sumed things  and  because  there  is  in  our  experience  nothing  analogous 
to  them  making  their  nature  intelligible  to  us ;  and,  finally,  useless  be- 
cause to  no  extent  verified  and  believed.  On  the  contrary,  our  investi- 
gation has  revealed  that  theories  derived  by  the  method  of  observation 
and  experiment  are  simple  in  the  sense  that  they  possess  few  or  no 
unintelligible  elements;  are  verifiable  from  the  fact  that  the  existences 
which  they  imply  out  of  experience  are  like  existences  in  experience  and 

[37] 


therefore  inferable  from  it ;  are  believable  because  based  upon  evidence 
which  can  be  repeatedly  tested,  and  because  the  things  implied  to  exist 
out  of  experience  are  like  things  in  experience  and  therefore  compre- 
hensible to  us;  and,  finally,  useful  because  verifiable,  believable,  and 
applicable  to  situations  in  our  experience. 

If  then  our  investigation  has  been  based  upon  typical  examples  of 
methods  of  thinking  and  has  been  sufficiently  thorough,  we  can  warn 
the  thinker  against  the  method  of  assumption  and  deduction  which  gives 
rise  to  unbelievable  and  useless  theories,  and  recommend  to  him  the 
method  of  experiment  and  inference,  which  yields  a  theory  believ- 
able and  of  practical  value. 

We  have  from  this  study  of  methods  of  thinking,  arrived  at 
conclusions  concerning  the  qualities  of  theories  and  the  relative 
merits  of  the  methods  by  which  they  were  derived.  With  that  our 
investigation  is  concluded. 

However,  another  problem,  closely  related  to  the  one  consid- 
ered, has  occurred  to  the  writer,  and  although  a  solution  of  it  would 
require  other  material  and  a  much  wider  research  than  has  been  here 
presented,  yet  a  statement  of  the  problem  may  be  of  value. 

We  may  safely  consider  that  each  thinker  who  presents  a 
theory  to  the  world  for  its  sanction,  has  faith  in  his  own  method  of 
thinking,  and  in  the  conclusions  at  which  he  has  arrived.  What 
differences  are  there  in  the  mental  make-up  of  thinkers,  which  will 
account  for  such  diverse  methods  of  thinking  and  for  such  diverse 
susceptibilities  to  belief  in  different  kinds  of  theories?  Three  of  the 
theories  which  we  studied  were  concerned  with  the  nature  of  matter, 
one  with  the  nature  of  organic  life,  one  with  the  nature  of  knowl- 
edge, and  one  with  the  existence  of  life  after  death.  Was  it  the 
problem  which  determined  the  method  of  thinking?  Would  Dar- 
win have  reasoned  as  Hyslop  did,  had  he  dealt  with  the  question  of 
life  after  death?  Or,  had  Norman  Lockyer  have  dealt  with  the 
question  of  the  nature  of  knowledge,  would  he  have  proceeded  as 
Locke  did  and  have  been  satisfied  with  Locke's  conclusions?  We 
have  determined  that  the  methods  used  by  Darwin  and  Lockyer 
were  applicable  to  the  problems  treated  by  Hyslop  and  Locke  and 
vice  versa ;  yet  Darwin  and  Lockyer  applied  one  method,  and  Locke 
and  Hyslop  another,  and  each  apparently  felt  that  his  method  was 
the  natural,  ready  and  secure  methods  of  reaching  the  truth. 

Men  have  been  roughly  classified  into  thinking,  willing  and 
feeling  men,  according  as  the  propensity  for  thinking,  willing  or  feel- 
ing predominated.  Will  these  broad  differences  in  mental  tendency 
account  for  the  different  manners  in  which  men  theorize?  Can  we 
say  that  Hyslop  believes  in  his  conclusions,  which  have  slight  foun- 

[38] 


elation  as  logical  inferences,  because  his  eagerness  for  accomplish- 
ment caused  him  to  accept  the  first  theory  with  a  semblance  of 
strength  and  blinded  his  judgment  for  the  value  of  evidence?  or 
shall  we  say  his  judgment  was  blinded  because  his  conclusions  were 
so  dear  to  him  that  he  must  give  them  a  foundation  in  reason  at  any 
cost?  Or  shall  we  say  that  from  a  religious  nature  and  early  train- 
ing his  conclusions  became  beliefs  long  before  he  attempted  to 
theorize  about  them,  and  that  in  his  theory  he  simply  presents  his 
beliefs  and  such  excuse  in  reason  as  he  can  find  for  them? 

And  shall  we  explain  Locke's  conclusions  and  method  of  think- 
ing by  saying  that  his  judgment  for  the  value  of  evidence  was  over- 
powered because  he  was  eager  to  explain  for  the  sake  of  accom- 
plishment, or  because  his  conclusions  were  dear  to  him  and  he 
wished  to  give  them  support?  Or  shall  we  conclude  that  his  educa- 
tion made  certain  conceptions  habitual  with  him,  and  that  he  ac- 
cepted them  as  the  foundation  of  his  theory,  without  criticism,  be- 
cause he  never  questioned  their  self-evidence? 

Perhaps  we  could  explain  Darwin's  and  Lockyer's  methods  of 
theorizing  by  finding  that  there  is  a  predominately  thinking  man; 
and  that  his  keen  appreciation  of  the  value  of  evidence  and  of  clear 
thinking  will  not  permit  of  his  accepting  as  facts  the  conceptions 
which  his  education  has  given  him  without  foundation  in  evidence; 
and  will  not  allow  of  his  leaving  his  conceptions  vaguely  defined. 
We  may  find  that  the  appreciation  which  such  a  man  has  for  the 
value  of  evidence  and  for  the  requirements  of  sound  thinking  is 
such  that  neither  his  desire  for  accomplishment  nor  his  desire  that 
certain  things  should  be  proved  true  can  overpower  his  judgment  as 
a  thinking  man  and  cause  him  to  be  satisfied  with  unfounded  assump- 
tions and  vaguely  defined  or  unintelligible  conceptions. 

The  solution  of  this  problem  would  be  of  great  value.  For  if 
trustworthy  conclusions  could  be  reached  in  its  solution,  education 
could  more  exactly  aim  to  correct  those  tendencies  in  thinking  which 
cause  men  to  expend  great  and  earnest  efforts  in  creating  an  un- 
believable and  useless  theory,  while  others  more  fortunate  in  their 
choice  of  methods,  or  by  education  and  endowment  more  wise,  with 
no  more  effort  and  no  more  concern  for  the  truth  and  human  good, 
create  theories  which  become  instruments  for  the  transformation  of 
thought  and  for  the  general  advancement  of  human  welfare. 


[39] 


VITA. 

The  author  of  this  dissertation,  Lucas  Carlisle  Kells,  was  born 
at  Sauk  Centre,  Minnesota,  June  1 7th,  1 882.  He  graduated 
from  the  High  School  of  Sauk  Centre,  Minnesota,  in  June,  1899. 
He  entered  the  University  of  Minnesota  September,  1 899,  and 
studied  there  until  June,  1904,  attending  graduate  courses  in  Phi- 
losophy under  Professor  Norman  Wilde  and  Professor  David 
Swenson,  and  in  Education  under  Professor  George  F.  James,  dur- 
ing the  year  1903-1904.  He  received  the  degrees  of  A.  B.  and 
A.  M.  in  1904.  He  entered  the  University  of  Columbia  in  New 
York  City  in  September,  1904,  and  attended  there  until  June, 
1909,  pursuing  graduate  courses  in  Philosophy  and  Psychology 
under  Professors  Woodbridge,  Dewey,  Fullerton,  Adler  and  Cat- 
tell  during  the  years  1904-1906.  In  September,  1906,  he  entered 
the  Columbia  Law  School,  from  which  he  received  the  degree  of 
LL.B.  in  June,  1909.  In  1904,  he  was  appointed  scholar  in  the 
department  of  Philosophy  at  the  University  of  Columbia,  and  in  the 
years  1907-8,  1908-9,  he  held  scholarships  in  the  School  of  Law 
of  Columbia  University. 


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